Drug allergy

BACKGROUND

Drug allergies occur when the body's immune system overreacts to substances in certain medications. These substances, called allergens, are normally harmless in individuals who do not have allergies.

Normally, the immune system helps the body fight against disease and infection. However, if the individual is allergic to a medication, the immune system attacks the medication because it is identified as a disease-causing substance, such as bacteria.

When the immune system launches an attack, symptoms of an allergic reaction develop. Several different types of allergic reactions may occur. Reactions may develop suddenly or be delayed. Reactions may be mild, causing hives or itchy skin. In some cases, drug allergies may be potentially life threatening. The most severe type of allergic reaction, known as anaphylaxis, may occur immediately after taking a drug. The most serious symptoms of anaphylaxis include difficulty breathing, increased heart rate, and decreased blood pressure, all of which can be fatal if left untreated.

CAUSES

General: Allergic reactions can be classified into four immunopathologic categories using various classification systems. The Gell and Coombs allergic classification system is based on the immune system's response to the allergen, not on the severity of the reaction.

Type I: Typically, a type I allergic response (also called a hypersensitivity reaction) is not triggered the first time the body encounters the allergen in the medication. In fact, some people can be repeatedly exposed to the allergen before an allergy develops. The first time or several times after the body is exposed to the allergen, the immune system becomes sensitized. During this process, the body's white blood cells develop immunoglobulin E (IgE) antibodies to the drug allergens.

Once sensitized, the antibodies quickly detect and bind to the allergens the next time they enter the body. These antibodies also trigger the release of chemicals, including histamine, which cause allergic symptoms, such as hives, inflammation, itchy skin, and possibly anaphylaxis. Anaphylaxis is a severe allergic reaction that affects many body parts. Symptoms of anaphylaxis include low blood pressure, difficulty breathing, shock, and loss of consciousness. Symptoms of anaphylaxis can vary from mild to severe and may be life threatening without immediate treatment.

In rare instances, an initial dose is enough to sensitize the body's immune system. Other individuals may take a drug for several days without any problems, and then have a reaction when the drug is taken in the future. Also, once sensitized to a specific drug it is possible to develop an allergic reaction to a related drug, even when it is taken for the first time.

Type II: A type II allergic reaction is typically called a cytotoxic reaction because it involves the destruction of the host cells. An antigen associated with a specific cell initiates cytolysis (breakdown of the cell) by an antigen-specific antibody, such as immunoglobulin G (IgG) or immunoglobulin M (IgM). This reaction often involves blood elements, such as red blood cells, white blood cells, or platelets. It often occurs within five to 12 hours of exposure to the allergen, which may include penicillin, quinidine, phenylbutazone, thiouracils, sulfonamides, or methyldopa.

Type III: During a type III allergic reaction, patients develop an antigen-antibody immune complex, which deposits on blood vessel walls and activates cell components called complements. This causes a serum sickness-like syndrome, involving fever, swelling, skin rash, and enlarged lymph nodes, in about three to eight hours. It may be caused by a variety of allergens, including penicillin, sulfonamides, intravenous (IV) contrast media, and hydantoins.

Type IV: Type IV allergic reactions involve delayed cell-mediated reactions. Antigens on the allergen release inflammatory mediators within 24 to 48 hours of exposure. This type of reaction is seen with graft rejection, latex, contact dermatitis, and tuberculin reaction.

COMMON TRIGGERS

Antibiotics: Most drug allergies are caused by an antibiotic called penicillin. This drug is commonly used to treat ear infections and strep throat. Patients who are allergic to penicillin may also be allergic to related drugs, including amoxicillin, ampicillin, dicloxacillin, nafcillin, penicillin G, or penicillin V.

Another group of antibiotics, called sulfonamides, may cause allergic reactions. Examples of sulfonamides include sulfamethoxazole (Thiosulfil Forte©), sulfasalazine (Gantanol©), and sulfisoxazole (Azulfidine©).

Anti-seizure medications: Anti-seizure medications (anticonvulsants) may trigger an allergic reaction. Examples include phenytoin (Dilantin©) and carbamazepine (Tegretol©).

Pain killers: Pain killers, such as nonsteroidal anti-inflammatories (e.g. ibuprofen), codeine, and morphine, may cause an allergic reaction. Local anesthetics, such as Novocain©, may also trigger an allergic reaction.

Insulin preparations: Insulin preparations (especially from pork and beef) that are used to treat diabetes may cause an allergic reaction.

Other: Patients should always check the inactive ingredients of their medications and tell their healthcare providers if they have a history of any type of allergy. This is because some drugs are made with fillers, such as lactose, that may trigger an allergic reaction. For instance, there have been cases of asthmatic patients with severe milk allergies that developed life-threatening allergic reactions after using a lactose-containing medicine called Advair Diskus©.

RISK FACTORS

Individuals who have a family history of allergies or asthma.

Individuals who are frequently exposed to the allergy-causing drug.

There is a higher risk of allergic reaction if the drug is taken in large dosages.

There is a higher risk of allergic reaction if the drug is injected.

OTHER DRUG REACTIONS

Adverse effects: Not all adverse reactions to drugs are allergies. In fact, less than 10% of adverse drug reactions are allergic because they do not involve the immune system. Instead, the drug directly affects various organs throughout the body.

For instance, a nasal decongestant constricts the capillaries in the nose in order to reduce swelling in the nose and open the airway passages. However, a side effect is that it also constricts the capillaries in other regions of the body, which may lead to an increased heart rate, headache, or dizziness. Since a decongestant is not specific to a single part of the body or one single action, some patients may experience side effects. Since these symptoms do not involve the immune system, it is considered an adverse effect, not an allergic reaction.

Other causes of adverse reactions include interactions between two or more drugs, overdose, or the body's inability to break the drug down completely in the body as a result of liver or kidney damage. For instance, pain relievers, such as oxycodone or codeine, may cause profound nausea, vomiting, constipation, and hives. However, none of these symptoms are true allergies.

Aspirin allergy: Non-allergic drug reactions, such as aspirin-induced asthma, may cause symptoms similar to an allergic reaction. Aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Advil© or Motrin©), may cause asthma symptoms, stuffy nose, watery eyes, and, occasionally, facial flushing and swelling in about 10% of asthmatics. However, the immune system is not involved in aspirin-sensitive asthma. Asthmatics and especially asthmatics who also have nasal polyps, are vulnerable to asthma as a side effect of aspirin and aspirin-like drugs.

In the body, these drugs inhibit the cyclooxygenase-1 (COX-1) enzyme, which produces inflammation and fever. Their ability to inhibit the enzyme allows NSAIDs to reduce pain, inflammation, and fever. Inhibiting the enzyme also allows NSAIDs to clear the way for different enzymes that have adverse effects in some people. One of these enzymes triggers the release of chemicals that can cause the airways to swell and increase mucus production, leading to an asthma attack. The process is an unwanted side effect of NSAIDs, not an immune-system reaction to NSAIDs

SYMPTOMS

General: Several different types of allergic reactions may occur. The severity of an allergic reaction to medication can range from mild to severe. Although drug allergies can be life threatening, death from an allergic reaction to a medication is rare. The skin is most commonly involved.

Unlike most allergic reactions, allergic reactions to drugs usually occur days or weeks after the first dose of the drug is given.

Common symptoms: Common symptoms typically include hives, rash, sensitivity to light, red and itchy patches of skin that sometimes occur with swelling of the face or tongue, fever, muscle and joint aches, enlarged lymph nodes, kidney inflammation, difficulty breathing, chest tightness, wheezing, throat tightness, fainting or light-headedness, loss of consciousness, rapid or irregular heartbeat, and swelling of the face/tongue/lips/throat/joints/hands/feet may occur.

Anaphylaxis or anaphylactic reaction: Anaphylaxis is a serious systemic allergic reaction that can be life threatening. Signs of an anaphylactic reaction may include itching and hives over large areas of the body, swelling in the throat or tongue, difficulty breathing, dizziness, stomach cramps, nausea, or diarrhea. An individual with anaphylaxis should seek emergency medical care as soon as symptoms appear. Anaphylactic reactions typically occur within one hour of taking the drug and may even occur within minutes. However, in some cases, it may take up to four hours after the first dose of the drug for anaphylactic reactions to occur.

DIAGNOSIS

General: Most drug allergies are diagnosed after a healthcare provider observes the patient's signs and symptoms. Patients should tell their healthcare providers if they are taking any new drugs (prescription or over-the-counter) or if they have a history of allergies.

Patients who experience symptoms of anaphylaxis after taking a medication are treated with epinephrine immediately. Because anaphylaxis is life threatening, a diagnosis is not needed to begin urgent medical treatment. If it is unclear whether or not the patient has a drug allergy, tests may be performed.

Skin test: A skin test may also be performed. During the test, the skin is exposed to allergens from medications that may be causing symptoms. A diluted form of the allergen may be scratched onto the skin's surface, injected under the skin, or applied to a patch that is stuck onto the skin. The skin is then observed for an allergic reaction. If the allergen triggers an allergic reaction, 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.

A skin test is typically conducted in a healthcare provider's office. Skin tests cause minimal, if any, discomfort. The needles used during a scratch test barely penetrate the skin's surface and will not cause bleeding.

Allergen-specific immunoglobulin (IgE) test: An allergen-specific immunoglobulin E (IgE) test, commonly referred to as the radioallergosorbent test (RAST©), may also be used to determine whether the patient is allergic to certain allergens in medications.

During the procedure, a sample of blood is taken from the patient and sent to a laboratory and tested. Patients that test positive for immunoglobulin E (IgE) are diagnosed with drug allergies.

A qualified healthcare provider will interpret the results of the test. In general, the sensitivity of these tests ranges from 50-90%, with the average being about 70-75%. The patient will receive test results in about 7-14 days.

TREATMENT

General: Patients who experience drug allergies should stop taking the offending medication under the supervision of their healthcare providers. The drug should not be taken in the future because an allergic reaction will most likely occur again. Patients should tell their healthcare providers if they have ever experienced an allergic reaction to a drug (prescription or over-the-counter).

Antihistamines: Antihistamines, such as diphenhydramine (Benadryl©) may help reduce mild allergy symptoms, including hives and itchy eyes. Diphenhydramine may be injected when quick action is needed during a severe allergic reaction. It may be taken by mouth to treat less severe reactions.

Corticosteroids: Corticosteroids are usually given through an IV (intravenously) at first in order to quickly reverse the effects of the chemical mediators (e.g. histamine) that are responsible for causing allergy symptoms. These drugs reduce swelling and many other symptoms of allergic reactions. Individuals 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, such as hives.

Epinephrine: Epinephrine is only used to treat a very severe allergic reaction, called anaphylaxis. Epinephrine, which helps open the breathing tubes, is injected into the patient. This medicine also constricts the blood vessels, which increases blood pressure. Patients who experience anaphylaxis may also be admitted to the hospital to have their blood pressure monitored and possibly to receive breathing support. Some patients may need to have a breathing tube placed through the nose or mouth. In severe cases, emergency surgery that involves placing a tube directly into the trachea may be necessary.

Individuals with a history of severe drug allergies should carry a prescription epinephrine auto-injector. If symptoms of anaphylaxis appear after exposure to an allergen, the patient uses the device to inject the epinephrine into his/her thigh. A trained family member or friend may help the patient administer the epinephrine, if necessary. After using an epinephrine auto-injector, patients should immediately go to the emergency department or the nearest hospital.

Less severe allergic reactions that affect breathing may be treated with an inhaled epinephrine bronchodilator. An epinephrine bronchodilator should only be used to treat allergic reactions. It should not be used to treat chronic asthma symptoms because it may cause adverse effects.

INTEGRATIVE THERAPIES

Note : Anaphylaxis is considered a medical emergency that requires immediate medical care. Therefore, integrative therapies should never be used in place of conventional medicine when an individual experiences an anaphylactic-like reaction.

Good scientific evidence :

Bromelain : Some physicians use bromelain, an enzyme derived from pineapple, to help reduce inflammation. It is sometimes recommended to be taken with turmeric (Curcuma longa), which may enhance the effects of bromelain.

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.

Unclear or conflicting scientific evidence :

Black seed : Studies in patients with allergies found that black seed decreased allergic disease severity. However, 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 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 : Cat's claw may have anti-inflammatory effects, which has led to research of this herb for conditions such as allergies. Large, high-quality human studies are needed comparing effects of cat's claw alone vs. placebo.

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.

Dandelion : Research in laboratory animals suggests that dandelion root may possess anti-inflammatory properties. There is a lack of well-conducted human studies currently available in this area.

Avoid if allergic to chamomile, feverfew, honey, yarrow, or any related plants such as aster, daisies, sunflower, chrysanthemum, mugwort, ragweed, or ragwort. Use cautiously with diabetes or bleeding disorders, gastroesophageal reflux disease (GERD), kidney or liver diseases, or a history of stroke or electrolyte disorders. Potassium blood levels should be monitored. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk and do not use immediately after these procedures. Avoid if pregnant or breastfeeding.

Eyebright : Several iridoid glycosides isolated from eyebright, particularly aucubin, may possess anti-inflammatory properties comparable to those of indomethacin (a nonsteroidal anti-inflammatory drug). However, there is currently insufficient evidence to recommend for or against eyebright as an anti-inflammatory agent.

Avoid with a known allergy or hypersensitivity to eyebright. Hypersensitivity to members of the Scrophulariaceae family may lead to a cross-sensitivity reaction. Use cautiously as an eye treatment, particularly homemade preparations, due to the risk of infection if not sterile. Use cautiously with diabetes and drugs that are broken down by the liver. Avoid if pregnant or breastfeeding.

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 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.

Licorice : Many medical conditions are marked by inflammation. Because licorice can affect the metabolism of steroids, licorice is sometimes used to help decrease inflammation. Additional study is needed to make a conclusion.

Avoid with a known allergy to licorice, any component of licorice, or any member of the Fabaceae (Leguminosae) plant family. Avoid with congestive heart failure, coronary heart disease, kidney or liver disease, fluid retention, high blood pressure, hormonal abnormalities or if taking diuretics. Licorice can cause abnormally low testosterone levels in men or high prolactin or estrogen levels in women. This may make it difficult to become pregnant and may cause menstrual abnormalities.

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 inflammatory skin disorders. Additional research is needed.

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 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.

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.

Turmeric : Turmeric is a perennial plant native to India and Indonesia, and it is often used as a spice in cooking. Laboratory and animal studies show activity against inflammation for turmeric and its constituent curcumin. Reliable human research is lacking.

Avoid if allergic or hypersensitive to turmeric (curcumin), yellow food colorings or plants belonging to the Curcuma or Zingiberaceae (ginger) families. Use cautiously with history of bleeding disorders, immune system deficiencies, liver disease or gallstones. Use cautiously with blood-thinners (e.g. warfarin). Use cautiously if pregnant or breastfeeding.

Traditional or theoretical uses lacking sufficient evidence :

Acupuncture : Some clinicians claim that acupuncture may help boost the immune system and lessen the frequency or severity of allergic responses like angioedema. However, more scientific research is needed before any recommendations can be made for allergies.

Needles must be sterile in order to avoid disease transmission. Avoid with valvular heart disease, infections, bleeding disorders, medical conditions of unknown origin, or neurological disorders. Avoid if taking drugs that increase the risk of bleeding (e.g. anticoagulants). Avoid on areas that have received radiation therapy and during pregnancy. Use cautiously with pulmonary disease (e.g. 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 because therapy may interfere with the device.

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.

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.

Devil's claw root : Devil's claw root may help reduce inflammation and skin lesions. Additional research is needed regarding anti-inflammatory effects.

Avoid if allergic to devil's claw or to plants in the Harpagophytum procumbens family. Use caution with stomach ulcers or history of bleeding disorders, diabetes, gallstones, gout, heart disease, stroke, ulcers, or with prescription drugs used for these conditions. Stop use two weeks before surgery/dental/diagnostic procedures with bleeding risk, and do not use immediately after these procedures. 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.

Ginkgo biloba : Ginkgo biloba extract has been used for allergies and inflammation. However, in rare cases, Ginkgo has been reported to cause an allergic reaction on the skin.

Avoid if allergic or hypersensitive to members of the Ginkgoaceae family. If allergic to mango rind, sumac, poison ivy or oak or cashews, then allergy to ginkgo is possible. Avoid with blood-thinners (like aspirin or warfarin (Coumadin©)). Ginkgo seeds are dangerous and should be avoided. Skin irritation and itching may also occur due to ginkgo allergies. Do not use ginkgo in supplemental doses if pregnant or breastfeeding.

Goldenseal : Goldenseal (Hydrastis canadensis) has been used as an antihistamine and to treat severe symptoms of allergies like stomach pain, diarrhea, and decreased appetite.

Avoid if allergic or hypersensitive to goldenseal or any of its constituents, like berberine and hydrastine. Use cautiously with bleeding disorders, diabetes, or low blood sugar. 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 : 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.

Quercetin : Quercetin, a naturally occurring flavonoid, may reduce the likelihood of a reaction to allergies. The recommended amount is generally 200 to 400 miligrams three times daily before meals, according to a review by the University of Maryland Medical Center. Avoid citrus-based forms of flavonoids if sensitive to citrus or if taking calcium-channel blockers to treat high blood pressure.

Quercetin is generally considered safe when taken at doses normally found in foods. Avoid if allergic or hypersensitive to quercetin. Possible eye, skin, gastrointestinal and/or respiratory tract infection may occur. Avoid if pregnant or breastfeeding.

PREVENTION

The more exposure the body has to medications, the greater the likelihood of experiencing an allergic reaction to medication.

Do not take a medication that has caused an allergic reaction in the past. Once an individual has had a reaction to a drug, the risk of having a more severe reaction in the future increases dramatically.

Patients should make sure that any reactions they have had to medications is documented. Even if this information is included in the patient's medical chart, patients should still inform their healthcare providers, including their dentists, about their allergies and the types of reactions they have had to medications. Patients should tell their healthcare providers if they are taking any drugs (prescription, over-the-counter), herbs, or supplements.

Individuals with a history of anaphylaxis should carry an auto-injectable epinephrine device, called an EpiPen©, with them at all times. A trained family member or friend may help the patient administer the epinephrine, if necessary. Once the epinephrine auto-injector is used, patients should immediately go to the emergency department of the nearest hospital.

Consider wearing a medical alert ID bracelet or necklace. These items can alert medical personnel and others about the risk of an allergic reaction. Also, adults can carry a card that contains important medical information.

AUTHOR INFORMATION

This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

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