Urticaria, also known as hives, is characterized by red, raised itchy welts (wheals) of varying sizes on the surface of the skin. The small bumps may look similar to mosquito bites, and they tend to occur in clusters. Hives are among the most common symptoms of an allergic reaction.
The lesions of hives are caused by inflammation in the skin. Many allergens, including foods and medications, trigger allergic reactions that cause urticaria. Hives appear after the body releases histamine, triggering an allergic reaction. Researchers estimate that 15-20% of Americans experience hives as part of an allergic reaction. Medical conditions including autoimmune disorders, infections, and physical factors may cause hives.
In most cases, hives are harmless and do not leave any lasting marks, even without treatment. However, caution is advised because an allergic reaction can progress into more serious symptoms like difficulty breathing. Also, once a person is sensitized, the reaction may be worse on subsequent exposure to an allergen.
Treatment varies depending on the underlying cause and severity of the symptoms. Allergy medications may include antihistamines or leukotriene receptor antagonists. Intravenous immune globulin (IVIG), made of antibodies extracted from pooled blood donations from hundreds to thousands of donors, may help treat autoimmune disorders and allergen immunotherapy (allergy shots) may help reduce the body's sensitivity to certain substances.
URTICARIA AND ANGIOEDEMA
Urticaria (hives) and angioedema are different manifestations of the same pathologic process. In both conditions, the small veins in the body become swollen, causing fluid leakage and edema (swelling). However, urticaria is localized to the superficial portion of the dermis layer of the skin, while angioedema involves vessels in the layers of the skin below the dermis.
Urticaria is characterized by round wheals with raised, swollen, red edges, and a central blanching (whitening). Because angioedema occurs below the skin, it causes well-demarcated, localized, non-pitting edema. Pitting edema occurs when a bump on the skin is pressed down and it remains indented for a certain length of time.
Urticaria and angioedema can occur together or separately. Recurrent episodes of one or both conditions for less than six weeks are considered acute, whereas longer-lasting outbreaks are considered chronic.
TYPES OF URTICARIA
Ordinary urticaria: Ordinary urticaria can be caused by exposure to an allergen, or the cause may be unknown. It is the most common form of urticaria. This form can be either acute or chronic. Acute ordinary urticaria typically only lasts a few days. Infections (like the flu) or allergic reactions to substances such as food or medicine may lead to acute urticaria. Chronic urticaria lasts for more than six weeks and the cause is often unknown.
Physical urticaria: Sunlight, heat, cold, water, pressure, vibrations, or exercise may cause what is known as physical urticaria. Solar urticaria (in response to sunlight) forms within minutes of sun exposure and typically fades after one to two hours. Cold urticaria appears when the skin is warmed after exposure to cold.
Dermatographic urticaria: Dermatographic urticaria forms after the skin has been firmly stroked or scratched. This form can often occur with other types of urticaria and may last for months or even years. Most patients with dermatographic urticaria are otherwise healthy.
General: Many allergens, including foods and medications, can trigger allergic reactions that cause urticaria (hives). The more exposure a person has to common allergens, the greater the chance that he/she will become allergic. That is why occupational exposure to allergens is a common cause of hives. For instance, bakers are more likely to develop allergies to yeast, flour, or grains, and landscapers are more likely to develop allergies to pollen. Medical conditions including autoimmune disorders, infections, and physical factors may cause hives.
Antibody production: Urticaria may occur in response to the body's production of antibodies. Antibodies are proteins produced by the immune system to fight specific bacteria, viruses or other foreign substances that enter the body. This might occur as the result of blood transfusions, immune system disorders (like lupus or cancer), certain thyroid disorders, or infections (as serious as hepatitis or as mild as a cold).
Animal dander: Animals secrete oily fluids from their skin, which contain allergens called dander. These fluids collect on fur, feathers, and other surfaces inside the home causing allergic reactions in sensitive people. Proteins in the animal's saliva also cause allergic reactions. These allergens are so small that they may become airborne for extended periods of time
Autoimmune disorders: Autoimmune disorders, such as systemic lupus erythematosus (SLE), account for up to 50% of all cases of chronic urticaria, according to researchers. Autoimmune disorders are conditions caused by an immune response against the body's own tissues. The immune system mistakes its own cells for foreign invaders like bacteria or viruses.
Foods: Food allergens are those parts of foods, usually proteins, which lead to allergic reactions that may cause hives. Most allergens can still cause allergic reactions even after they are cooked or have been digested. However, some allergens (usually from fruit and vegetables) only cause allergic reaction if eaten raw. These reactions are usually limited to the mouth and throat. According to the American Academy of Allergy, Asthma & Immunology (AAAAI), six foods, including milk, peanuts, soy, eggs, wheat, and tree nuts (like pecans and walnuts), cause 90% of food allergies in children. Children usually outgrow allergies to milk, eggs and soy, but peanut, tree nut, fish and shellfish allergies continue throughout adulthood.
Immune disorders: Other disorders of the immune system, including cryoglobulinemia, cryofibrinogenemia, syphilis, mastocytosis, Muckle-Wells syndrome, and familial cold auto-inflammatory syndrome, may cause hives.
Infections: Many infections may cause urticaria. Viral upper-respiratory tract infections (colds or URIs) are a common cause of hives in children. Other viruses, such as hepatitis (liver inflammation) and many bacterial and fungal infections, may cause urticaria as well.
Insect venom: The honeybee, yellow jacket, paper wasp, white-faced hornet (bald-faced hornet), and fire ant are among the most common insects that trigger insect sting or bite allergies that often result in hives. Since the stinger is a modified egg-laying apparatus, only females can sting.
Latex: Latex, a substance found in products like rubber gloves or condoms, can also trigger allergic reactions that cause hives. A component of the latex substance itself is an allergen. Latex reactions may cause a potentially life-threatening allergic reaction called anaphylaxis.
Medications: Almost any medication may cause hives. Antibiotics (such as penicillin), aspirin, ibuprofen (Advil© or Motrin©), glimepiride (Amaryl©), and blood pressure medications frequently cause allergic reactions. There can be cross sensitivity to a different medication in the same drug class.
Pollen: Each spring, summer, and fall, plants release tiny particles called pollen into the air in order to reproduce. Pollen from plants, such as ragweed, can trigger allergy symptoms, including hives.
Physical factors: Environmental factors, such as heat, cold, sunlight, water, pressure on the skin, emotional stress, and exercise, may also cause hives in some people.
Urticaria (hives) can be either acute or chronic. Acute hives can last less than a day or up to six weeks. Chronic hives may last longer than six weeks. In some cases, they can occur for months to years at a time. Hives cause red, itchy welts to form on the skin often accompanied by sensations of warmth. When urticaria forms in response to the cold or the water, symptoms may include wheezing, flushing, generalized hives, and fainting.
In rare instances, hyperpigmentation (darkening of the skin) or hypopigmentation (light spots of the skin) may also occur.
Drug-induced urticaria may cause severe heart and lung failure.
Individuals who have had hives before.
Individuals who have had other allergic reactions.
Individuals who have a disorder associated with hives and angioedema, such as lupus, lymphoma, or thyroid disease.
Individuals who have a family history of hives or angioedema.
Urticaria can be diagnosed after a physical examination and medical history. Healthcare providers will then conduct tests to determine the cause. Allergy testing with either skin tests or allergen-specific immunoglobulin E tests may be performed to detect specific allergies. A fluorescent antinuclear antibody test (FANA) may be performed to determine whether the condition is caused by an autoimmune disorder.
Skin test: A skin test is used to determine whether a patient is allergic to certain substances, such as mold, dust mites, or animal dander. During the test, the skin is exposed to different allergy-causing substances (allergens) and then observed for an allergic reaction. Some tests, like the percutaneous (puncture, prick, or scratch) test, detect immediate allergic reactions that develop within minutes of exposure to an allergen. Other tests, like the epicutaneous (patch) test, detect delayed allergic reactions that develop over the course of several days. If an allergen triggers an allergic reaction to a test, the patient will develop reddening, swelling, or a raised, itchy red wheal (bump) that looks similar to a mosquito bite. The healthcare provider will measure the size of the wheal and record the results. The larger the wheal, the more severe the allergy.
Allergen-specific immunoglobulin E (IgE) test: An allergen-specific immunoglobulin E (IgE) test, commonly referred to as radioallergosorbent test (RAST©), may also be used to determine whether the patient is allergic to specific substances. However, this test is less accurate than a skin test. It is usually performed in patients who have coexisting severe skin diseases (such as eczema or psoriasis) that make it difficult to interpret a skin test.
The in vitro test is conducted outside of the body in a laboratory setting. During the procedure, a sample of blood is taken from the patient. The blood is then sent to a laboratory that performs specific IgE blood tests. The allergen is bound to an allergosorbent (paper disc). Then the patient's blood is added. If the blood contains antibodies (immunoglobulins that detect and bind to antigens) to the mold antigens, the blood will bind to the allergen on the disc. A radiolabelled ANTI-IgE antibody is then added to the disc to measure the level of immunoglobulin E present in the blood. The higher the radioactivity, the higher the level of IgE in the blood and the more severe the allergy.
A qualified healthcare provider will interpret the results of the test. In general, the sensitivity of these tests range from 50-90%, with the average being about 70-75%. The patient will receive test results in about seven to 14 days.
Fluorescent antinuclear antibody test (FANA): The fluorescent antinuclear antibody test (FANA) is used to determine whether autoimmune disorders, such as systemic lupus erythematosus (SLE), scleroderma, Sj©gren's syndrome, Raynaud's disease, juvenile chronic arthritis, rheumatoid arthritis (RA), or antiphospholipid antibody syndrome, are causing hives. The FANA test is a blood test used to detect abnormal antibodies, called autoantibodies. The autoantibodies bind to components of and individual's own cells and cause the immune system to attack the body.
To measure results, human tissue culture cells (HEp-2 cell line) are grown in culture and applied to a microscope slide. The slides are then treated with methyl alcohol to make the cells permeable before they are combined with the patient's blood. The cells are incubated with fluorescent antibodies that detect the binding of human antibodies to the cells. The slide is then observed with a fluorescence microscope. The intensity of the staining and the binding pattern are scored at various dilutions.
A positive test result may suggest an autoimmune disease, but further testing is needed to make a specific diagnosis. FANA test results can be positive in people who do not have autoimmune diseases. While a false positive result is uncommon, the frequency increases as people age. A false negative result is also possible, but it is uncommon.
General: Mild symptoms may not need treatment. Acute attacks usually clear up within four days with or without medication. The symptoms of mild hives may be reduced by not irritating the affected areas, taking cool showers, applying cool compresses, wearing loose, light clothing, minimizing vigorous activity, and using over-the-counter antihistamines to help relieve the itching. Moderate symptoms may require treatment.
Antihistamines: The most common treatment for hives is antihistamine medication. Common nonprescription antihistamines include: diphenhydramine (Benadryl©), chlorpheniramine (Chlor-Trimeton©), clemastine (Tavist©), and loratadine (Alavert© or Claritin©). Antihistamines, such as diphenhydramine, chlorpheniramine, and clemastine, may cause drowsiness. Some antihistamines cause more sedation than others. Commonly used prescription medications include: desloratadine (Clarinex©), fexofenadine (Allegra©), cetirizine (Zyrtec©), and hydroxyzine (Atarax© or Vistaril©).
Allergen immunotherapy: Allergen immunotherapy, also known as allergy shots, is often used to treat patients who suffer from severe allergies, or for those who experience allergy symptoms more than three months a year. Allergen immunotherapy involves injecting increasing amounts of a diluted allergen into a patient over several months. Immunotherapy does not cure allergies, but it may help reduce the body's sensitivity to certain substances. During therapy, some patients may not experience any allergy symptoms.
Corticosteroids: Corticosteroids have been used to treat severe allergic reactions, often caused by drug or food allergens. Corticosteroids are usually given through an IV (intravenously) at first in order to quickly reverse the effects of the mediators (like histamine). These drugs reduce swelling and many other symptoms of allergic reactions. Patients may also need to take a corticosteroid in pill form for several days after the initial treatment. These drugs are often given for less severe reactions. Also, a corticosteroid cream or ointment may be used for skin reactions.
Leukotriene receptor antagonists: Leukotriene receptor antagonists block the action of leukotrienes, which are also important mediators of the allergic response. New leukotriene receptor antagonists, such as montelukast (Singulair©) and zafirlukast (Accolate©), can effectively treat allergy symptoms without some of the common side effects like drowsiness. These long-acting medications are taken once daily.
Intravenous immunoglobulin therapy (IVIG): Intravenous immunoglobulin therapy (IVIG) may be beneficial for patients who have autoimmune disorders like systemic lupus erythematosus (SLE). Intravenous immunoglobulin (IVIG) is made of antibodies extracted from pooled blood donations from hundreds to thousands of donors. The immunoglobulin is typically injected into the patient's vein for about two to four hours a day for two to seven days. The patient usually receives another single dose every 10-21 days or every three to four weeks depending on the severity of the condition. Patients typically start responding to treatment after about eight days. The effects of treatment are temporary. Therefore, continual treatments are necessary to help boost the immune system.
Unclear or conflicting scientific evidence :
Acupuncture : Acupuncture is commonly used throughout the world. According to Chinese medicine theory, the human body contains a network of energy pathways through which vital energy, called "chi," circulates. These pathways contain specific points that function like gates, allowing chi to flow through the body. Needles are inserted into these points to regulate the flow of chi. Acupuncture plus point-injection has been found beneficial for the treatment of hives, although more research is needed to confirm these findings.
Needles must be sterile in order to avoid disease transmission. Avoid with heart valve disease, infections, bleeding disorders, medical conditions of unknown origin, or neurological disorders. Avoid if taking drugs that increase the risk of bleeding. Avoid on areas that have received radiation therapy. Use cautiously with pulmonary disease (such as asthma or emphysema). Use cautiously in elderly or medically compromised patients, diabetics, or with history of seizures. Avoid electroacupuncture with arrhythmia (irregular heartbeat) or in patients with pacemakers. Avoid if pregnant.
Agrimony : It remains unclear whether agrimony can effectively treat cutaneous disorders and rashes. Further research is needed to determine if agrimony is safe and effective.
Avoid if allergic or hypersensitive to agrimony or its related species. When used as recommended, agrimony is considered to be safe. Avoid with bleeding disorders, kidney or liver disease, or diabetes. Use cautiously with drugs that lower blood pressure.
Applied kinesiology : Applied kinesiology is commonly used for food allergy diagnosis. However, there is conflicting scientific evidence as to whether applied kinesiology is an effective diagnostic tool. Further research is warranted before a firm conclusion can be drawn. Applied kinesiology techniques in themselves are generally considered to be safe. However, medical conditions should not be treated with AK alone, and should not delay appropriate medical treatment.
Black seed : Studies in patients with allergies found that black seed decreased allergic disease severity, slightly decreased plasma triglycerides (levels of fat within the blood), and slightly increased HDL cholesterol. The effect of black seed for allergies is still not clear and further study is required.
Avoid with a known allergy/hypersensitivity to black seed, its constituents, black seed oil, or to members of the Ranunculaceae family. Allergic contact dermatitis has been reported after topical use of black seed or the oil from the seed.
Bromelain : Bromelain has been shown to decrease inflammation, regulate the immune system, and have antiviral effects and may help treat skin rash.
Avoid if allergic to bromelain, pineapple, honeybee, venom, latex, birch pollen, carrots, celery, fennel, cypress pollen, grass pollen, papain, rye flour, wheat flour, or members of the Bromeliaceae family. Use cautiously with a history of bleeding disorders, stomach ulcers, or heart, liver, or kidney disease. Use caution before dental or surgical procedures or while driving or operating machinery. Avoid if pregnant or breastfeeding.
Butterbur : Preliminary research suggests that butterbur may not suppress allergic skin disease reactions when compared to the prescription drug fexofenadine (Allegra©), which does suppress these reactions. Additional study is needed. Use caution if allergic or sensitive to Petasites hybridus or other plants from the Asteraceae/Compositae family (like ragweed, marigolds, daisies and chrysanthemums). Raw, unprocessed butterbur plant should not be eaten due to the risk of liver or kidney damage or cancer. Avoid if pregnant or breastfeeding.
Calendula : Limited early research suggests that calendula extracts may reduce skin inflammation. Human studies are lacking in this area.
Avoid if allergic to plants in the Aster/Compositae family such as ragweed, chrysanthemums, marigolds, and daisies. Use cautiously in patients taking sedatives, blood pressure medications, cholesterol medications, blood sugar-altering agents, and immunomodulators. Use cautiously with diabetes and in children. Avoid if pregnant or breastfeeding.
Cat's claw : It has been suggested that cat's claw may help treat respiratory diseases involving allergies. However, there is limited scientific evidence to support this claim. More well-designed trials are needed to determine whether cat's claw is a beneficial treatment. Avoid if allergic to cat's claw or Uncaria plants or plants in the Rubiaceae family such as gardenia, coffee, or quinine. Avoid with a history of conditions affecting the immune system (such as AIDS, HIV, some types of cancer, multiple sclerosis, tuberculosis, rheumatoid arthritis, lupus). Use cautiously with bleeding disorders or a history of stroke, or if taking drugs that may increase the risk of bleeding. Discontinue use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. Cat's claw may be contaminated with other Uncaria species. Reports exist of a potentially toxic, Texan grown plant, Acacia gregii being substituted for cat's claw. Avoid if pregnant, breastfeeding, or trying to become pregnant.
Hypnotherapy, hypnosis : It has been suggested that hypnotherapy may be effective for allergies. However, further research is necessary to determine whether it is an effective treatment. Use cautiously with mental illnesses like psychosis/schizophrenia, manic depression, multiple personality disorder or dissociative disorders. Use cautiously with seizure disorders.
Jewelweed : Jewelweed has been used traditionally as a treatment for various types of contact dermatitis, including poison ivy/oak rashes and allergic dermatitis, however, human study indicates that it may not be effective for this use. Avoid if allergic or hypersensitive to jewelweed (Impatiens biflora), its constituents, or members of the Balsaminaceae family. Use cautiously if taking calcium supplements and with kidney stone disorders. Avoid consuming excess amounts of jewelweed due to reports of high mineral content, particularly calcium oxalate. Avoid if pregnant or breastfeeding.
Lactobacillus acidophilus : Limited available study suggests that the Lactobacillus acidophilus (L. acidophilus) strain L-92 (L-92) may be effective for the treatment of Japanese cedar-pollen allergy. Further research is needed to confirm these results. L. acidophilus may be difficult to tolerate if allergic to dairy products containing L. acidophilus. Avoid with history of an injury or illness of the intestinal wall, immune-disease, or heart valve surgery. Avoid with prescription drugs, such as corticosteroids, because of the risk of infection. Use cautiously with heart murmurs. Antibiotics or alcohol may destroy L. acidophilus. Therefore, it is recommended that L. acidophilus be taken three hours after taking antibiotics or drinking alcohol. Some individuals may use antacids, such as famotidine (Pepcid©) and esomeprazole (Nexium©), to decrease the amount of acid in the stomach one hour before taking L. acidophilus.
Marshmallow : Marshmallow extracts have traditionally been used to treat inflammatory skin conditions. Several laboratory experiments, mostly in the 1960s, reported marshmallow to have anti-inflammatory activity but limited human study is available. Safety, dosing, and effectiveness compared to other anti-inflammatory agents have not been examined.
Historically, marshmallow is generally regarded as being safe in healthy individuals. However, since studies have not evaluated the safety of marshmallow, proper doses and duration in humans are not known. Allergic reactions may occur. There is not enough scientific evidence to support the safe use of marshmallow during pregnancy or breastfeeding.
Onion : Early research shows that topical application of an alcoholic onion extract significantly reduced responses to allergies, such as wheals (hives) and flares. More research is needed.
Avoid if allergic or hypersensitive to onion (Allium cepa), its constituents, or members of the Lilaceae family. Use cautiously with hematologic (blood) disorders, diabetes, hypoglycemia (low blood sugar), and hypotension (low blood pressure). Use cautiously if taking anticoagulants or antiplatelets (blood thinners). Avoid medicinal doses if pregnant or breastfeeding.
Para-aminobenzoic acid : Para-aminomethylbenzoic acid (PABA) may be useful in the treatment of lichen slerosus, a benign, progressive dermatologic condition characterized by inflammation, pruritus (itching), and pain, especially in the anogenital region (involving the anus and genitals). Additional investigations are needed regarding the use of PABA for inflammatory skin disorders.
Avoid with known hypersensitivity to PABA or its derivatives. Discontinue use if rash, nausea, or anorexia occurs. Avoid oral use in children and pregnant or nursing women. Use cautiously in patients with renal or liver disease. PABA should not be given concurrently with sulfonamides. Use cautiously in patients with bleeding disorders or taking anticoagulants. Use cautiously in patients with diabetes or hypoglycemia.
Peony : Peony root may have beneficial effects on immune function. These effects may help decrease inflammation associated with allergic skin reactions such as allergic dermatitis. There is currently not enough evidence to recommend for or against the use of peony in allergic skin conditions.
Avoid if allergic or sensitive to peony. Avoid with bleeding disorders or if taking drugs, herbs, or supplements that increase bleeding risk. Use cautiously with estrogen-sensitive cancers or if taking drugs, herbs, or supplements with hormonal activity. Avoid if pregnant or breastfeeding.
Perilla : Preliminary evidence suggests some benefit of perilla extract for seasonal allergies. Further clinical trials are required before conclusions can be made. Avoid if allergic/hypersensitive to perilla or members of the Lamiaciae/Labiatae family. Use cautiously with cancer, low HDL-cholesterol, and immune disorders. Use cautiously if taking NSAIDS or barbiturates. Avoid if pregnant or breastfeeding.
Probiotics : Only a few types and combinations of probiotics have been studied as a possible allergy treatment. They have been studied mostly in children, teenagers, and young adults. Further research is necessary before a firm conclusion can be made. Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
Stinging nettle : Limited available clinical study has examined the effectiveness of a topical combination product containing stinging nettle for insect bites. Results did not show a significant reduction in erythema or itching with the nettle-containing cream. Further well-designed clinical trials are required before a firm conclusion can be made.
Avoid if allergic or hypersensitive to nettle, the Urticaceae family, or any ingredient of nettle products. Use cautiously with diabetes, bleeding disorders, and/or low sodium levels in the blood. Use cautiously with diuretics and anti-inflammatories. The elderly should also use nettle cautiously because nettle may drastically reduce blood pressure. Avoid if pregnant because in one animal study, nettle caused uterine contractions. Avoid if breastfeeding due to insufficient evidence of safety.
Tea tree oil : Small studies show that tea tree oil applied to the skin may reduce allergic skin reactions caused by histamine-induced inflammation. Further research is needed to confirm these results.
Avoid allergic or hypersensitive to tea tree oil (Melaleuca alternifolia), any of its constituents, balsam of Peru, benzoin, colophony (rosin) tinctures, eucalyptol, or members of the Myrtle (Myrtaceae) family. Avoid taking tea tree oil by mouth. Avoid if taking antineoplastic agents. Use tea tree oil applied to the skin cautiously in patients with previous tea tree oil use. Avoid if pregnant or breastfeeding.
Thyme : Historically, thyme has been used topically for a number of inflammatory skin disorders. Results are mixed. Additional study is needed in this area.
Avoid with known allergy/hypersensitivity to members of the Lamiaceae (mint) family or to any component of thyme, or to rosemary (Rosmarinus officinalis). Avoid oral ingestion or non-diluted topical application of thyme oil due to potential toxicity. Avoid topical preparations in areas of skin breakdown or injury, or in atopic patients, due to multiple reports of contact dermatitis. Use cautiously in patients with gastrointestinal irritation or peptic ulcer disease due to anecdotal reports of gastrointestinal irritation. Use cautiously in patients with thyroid disorders due to observed anti-thyrotropic effects in animal research of the related species Thymus serpyllum. Avoid if pregnant or breastfeeding.
Thymus extract : Thymus extract may reduce allergy symptoms due to its potential immune stimulating effects. More clinical trials are required before recommendations can be made involving thymus extract for this use. Avoid if allergic or hypersensitive to thymus extracts. Use bovine thymus extract supplements cautiously due to potential for exposure to the virus that causes "mad cow disease." Avoid use with an organ transplant or other forms of allografts or xenografts. Avoid if receiving immunosuppressive therapy, with thymic tumors, myasthenia gravis (neuromuscular disorder), untreated hypothyroidism, or if taking hormonal therapy. Avoid if pregnant or breastfeeding; thymic extract increases human sperm motility and progression.
Witch hazel : A homeopathic formulation containing an extract of witch hazel and tinctures of other botanicals was studied for its effects in relieving redness and itching associated with mosquito bites. According to study results, the formulation did not provide effective relief from mosquito bite symptoms. However, because information about the strength or concentration of the witch hazel extract used was not available, and witch hazel was not evaluated alone, conclusions about the effects of witch hazel on symptoms of insect bites cannot be made. Additional research is needed in this area.
Avoid if allergic or sensitive to witch hazel. Avoid if pregnant or breastfeeding. Use cautiously in people with liver or kidney disorders, diabetes, and in children.
Zinc : Preliminary research on the effectiveness of zinc to treat skin conditions, including diaper rash. Further research is necessary before a firm conclusion can be made.
Zinc is regarded as relatively safe and generally well tolerated when taken at recommended doses and few studies report side effects. Zinc should only be given to pregnant or breastfeeding women under the supervision of their qualified healthcare providers.
Fair negative scientific evidence :
Applied kinesiology : Applied kinesiology (AK) has been used for diagnosis of allergies, but scant research has been done in this area. There is preliminary evidence suggesting that AK is not a reliable means of wasp venom allergy diagnosis. There is currently insufficient evidence on which to base recommendations for or against use of AK in this application. Applied kinesiology techniques in themselves are considered to be safe. However, medical conditions should not be treated with AK alone, and should not delay appropriate medical treatment.
Papain : A comparative controlled trial did not find a clinically or statistically significant difference between fire ant bites treated with papain or placebo.
Use cautiously in patients with bleeding disorders or taking anticoagulants or antiplatelets. Use cautiously with radiation therapy or in patients being treated for prostatitis. Avoid in patients with gastroesophageal reflux disease or in patients using immunosuppressive therapy. Avoid in patients allergic or sensitive to papain.
Traditional or theoretical uses lacking sufficient evidence :
Apple cider vinegar : Apple cider vinegar has been used traditionally as a topical treatment for insect stings, including bee stings. Scientific evidence supporting the use of apple cider vinegar for insect bites is currently lacking.
Apple cider vinegar is likely safe when taken by mouth as food flavoring. Use caution if allergic or hypersensitive to apple cider vinegar or any of its ingredients (like apples and pectin). Use caution with a history of low potassium levels, diabetes or osteoporosis. Avoid if pregnant or breastfeeding.
Burdock : Burdock is a plant that is native to Europe and northern Asia. The root is most often used in herbal preparations. Traditionally, burdock has been used to treat hives. However, there is currently no human evidence on its safety and effectiveness for this use.
Avoid if allergic to burdock or other plants of the Asteraceae/Compositae family (such as ragweed, chrysanthemums, marigolds, or daisies). Avoid with a history of dehydration, diabetes, heart disease, cancer, high blood pressure, or HIV. Stop use before and immediately after surgeries or dental or diagnostic procedures with bleeding risks. Avoid if pregnant or breastfeeding.
Chamomile : Although chamomile has traditionally been used to treat hives, scientific evidence is lacking. Based on anecdotal evidence, dried chamomile flowers have been added to bath water as a topical treatment for insect bites. Currently, human trials have not evaluated the safety or effectiveness of chamomile for these uses.
Avoid if allergic to chamomile or any related plants, such as aster, chrysanthemum, mugwort, ragweed, or ragwort. Stop use two weeks before and immediately after surgery/dental/diagnostic procedures with bleeding risks. Use cautiously if driving or operating machinery. Avoid if pregnant or breastfeeding.
Detoxification therapy (cleansing) : Detoxification is a broad concept that encompasses many different modalities and substances used in cleansing the body's systems and organs. Detoxification has been suggested as a possible treatment for hives. However, there is currently no scientific evidence of its safety or effectiveness for this use.
In cases of illness, the various forms of detoxification should be used under professional guidance. See specific monographs for precautions and warnings associated with modalities of detoxification.
Ephedra : Ephedra is a natural stimulant. Traditionally, ephedra has been used to treat hives. However, there is currently no evidence on the safety and effectiveness of ephedra for this use.
Even though this herb has been suggested as a potential treatment for hives, it is unsafe for humans. Serious reactions, including heart attack, stroke, seizure, and death have occurred. The U.S. Food and Drug Administration (FDA) has banned sales of ephedra dietary supplements. The FDA has collected more than 800 reports of serious toxicity, including more than 22 deaths. Avoid use in individuals younger than 18 years old. Avoid use for prolonged periods (longer than seven days) due to risk of abuse or toxicity. Discontinue use at least one week prior to major surgery or diagnostic procedures. Use cautiously with cardiovascular disease, including structural heart disease, arrhythmia, coronary artery disease, high blood pressure, cerebrovascular disease, and a history of stroke or transient ischemic attack. Use cautiously with depression, anxiety disorders, anorexia/bulimia, a history of suicidal ideation, insomnia, tremors, urinary retention, enlarged prostate, diabetes, kidney disease, glaucoma, thyroid disease, and peptic ulcer disease. Use cautiously with monoamine oxidase inhibitor (MAOI) or stimulant use. Avoid if pregnant or breastfeeding.
Kudzu : Kudzu is an herb that has been used in Chinese medicine for many years. Traditionally, kudzu has been used to treat hives. However, there is currently no scientific evidence on the safety and efficacy for this use.
No well-designed studies on the long-term effects of kudzu are available. Avoid if allergic or hypersensitive to Pueraria lobata or members of the Fabaceae/Leguminosae family. Use cautiously with blood thinners and blood pressure-lowering agents, hormones, antiarrhythmics, benzodiazepines, bisphosphonates, diabetes medications, drugs that are metabolized by the liver's cytochrome P450 enzymes, mecamylamine, neurologic agents, and methotrexate. Avoid if pregnant or breastfeeding.
Moxibustion : Moxibustion is a therapeutic method in traditional Chinese medicine, classical (five element) acupuncture, and Japanese acupuncture. During the therapy, an herb (usually mugwort) is burned above the skin or on the acupuncture points in order to introduce heat into an acupuncture point and alleviate symptoms. There is limited evidence suggesting that moxibustion may help treat hives. Additional research is needed to evaluate the safety and efficacy of moxibustion for this use.
Use cautiously over large blood vessels and thin or weak skin. Avoid with aneurysms, any kind of "heat syndrome," heart disease, convulsions, cramps, diabetic neuropathy, extreme fatigue and/or anemia, fever, or inflammatory conditions. Avoid use over allergic skin conditions, ulcerated sores, skin adhesions, or inflamed areas or organs. Do not use on contraindicated acupuncture points, the face, genitals, head, or nipples. Use cautiously in patients who have just finished exercising or taking a hot bath or shower. Use cautiously in elderly people with large vessels. Not advisable to bathe or shower for up to 24 hours after a moxibustion treatment. Avoid if pregnant or breastfeeding.
Peppermint oil : Peppermint is a flowering plant that grows throughout Europe and North America. Peppermint is usually grown for its fragrant oil. Historically, peppermint has been used to treat hives. Further research is needed to determine whether peppermint is safe and effective for this use.
Avoid if allergic or hypersensitive to peppermint or menthol. Peppermint is generally considered safe in non-allergic adults when taken in small doses. Use cautiously with G6PD deficiency or gallbladder disease. Menthol, which makes up part of peppermint oil, is generally considered safe in non-allergic adults. However, doses of menthol greater than 1 gram per kilogram of body weight may be deadly in humans. Avoid if pregnant or breastfeeding.
Probiotics : Probiotics are beneficial bacteria that are sometimes called friendly germs. They help maintain a healthy intestine and help the body digest foods. They also help keep harmful bacteria and yeasts in the gut under control. Most probiotics come from food sources, especially cultured milk products. Although probiotics have been suggested as a possible treatment for hives, there is insufficient scientific evidence on its safety and efficacy for this use.
Probiotics are generally considered safe and well tolerated. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
Avoid substances that trigger allergic reactions. Patients who are allergic to pollen should remain indoors in the morning and evening when outdoor pollen levels are highest.
To avoid stinging insects, it is important to learn what they look like and where they live. Avoid wearing sandals or walking barefoot in the grass. Do not drink from open beverage cans if outside. Stinging insects are attracted to sweet beverages and may crawl inside. Avoid wearing bright-colored clothing because stinging insects are attracted to vibrant colors.
Allergy testing with a trained specialist may help identify potential triggers.
Avoid unnecessary exposure to other environmental irritants such as insect sprays, tobacco smoke, air pollution and fresh tar or paint.
Patients should never take medications that are not prescribed for them.
Individuals should tell their healthcare providers and pharmacists if they have family histories of hives or angioedema.
Children who have been breastfed are less likely to develop allergies.
There is evidence that infants who are exposed to airborne allergens, such as dust mites and animal dander, may be less likely to develop related allergies.
Individuals with a history of a severe allergic reaction called anaphylaxis should carry an autoinjectable epinephrine device (known as an EpiPen©) with them at all times. A trained family member or friend may help the patient administer the epinephrine, if necessary.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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