A fever is an increase in normal body temperature. Healthy individuals typically have a body temperature of about 98.6 degrees Fahrenheit. The body temperature fluctuates by about one degree throughout the day. However, if a person's body temperature increases more than it normally does throughout the day, he/she has a fever. A person can usually recognize when he/she has a fever because it often causes symptoms, such as chills or sweating.
A fever is considered a sign of an underlying medical problem. Most fevers are caused by infections, such as the flu, pneumonia, or strep throat. Other common causes include extreme sunburn, exposure to hot environments, and certain medications. In rare cases, there may be no known underlying cause.
Fevers are usually not dangerous for adults, unless they are 103 degrees Fahrenheit or higher. For infants and very young children, even a slight increase in body temperature may indicate a serious infection. If a baby younger than 12 months old has a temperature higher than 100 degrees, a healthcare provider should be consulted immediately. Adults and children who have temperatures higher than 102 degrees that are not responding to medications, such as ibuprofen (Motrin©, Advil©), aspirin, or acetaminophen (Tylenol©), should visit their doctors.
Most fevers go away in a few days even without treatment. Additional treatments, such as antibiotics, may be necessary depending on the underlying cause of the fever.
General: A fever is usually a sign of an underlying medical condition. Below are some of the most common causes of fevers.
Infection: Most fevers are symptoms of an underlying viral or bacterial infection in the body. However, any type of infection, including fungal and parasitic infections, may cause fevers.
As the immune cells in the body fight off an infection, they generate heat, which leads to an increase in body temperature. Normally, part of the brain, called the hypothalamus, regulates the body's temperature. However, when an infection is present, substances called pyrogens prevent the brain from properly controlling the body's temperature. This is actually considered a positive response because the viruses that cause colds and other infections thrive in cool temperatures.
Extreme sunburn: Severe sunburn may cause a fever and chills.
Exposure to hot environments: Some people may develop a fever when the body becomes overheated. This condition, called hyperthermia, often occurs as a result of vigorous exercise or after exposure to extremely hot or humid weather. Hyperthermia is treated differently than other causes of fever. The affected person must be cooled immediately. The advanced stages of hyperthermia are commonly called heatstroke or sunstroke.
Medications: A fever may be a side effect of certain medications, such as antibiotics, blood pressure-lowering drugs, antidepressants, antihistamines, and drugs used to treat seizures. Some infants and young children develop fevers after receiving routine immunizations, such as the diphtheria, tetanus, and acellular pertussis (DTaP) vaccine.
Unknown origin: In some cases, there is no known cause of a fever. If a person has a body temperature higher than 100.9 degrees Fahrenheit with no known cause, a doctor may diagnose the condition as "fever of unknown origin." In such cases, treatment focuses on reducing the fever, rather than the underlying cause.
SIGNS AND SYMPTOMS
General: The duration and severity of a fever vary, depending on the cause. Patients who have a fever may experience chills, increased sweating, shivering, and warm skin.
Additional symptoms: Additional symptoms may also be present, depending on the cause. For instance, if a viral infection, such as the flu, is causing a fever, additional symptoms may include a runny nose, sore throat, headache, aching joints and muscles, nausea, and vomiting. Symptoms of hyperthermia may include confusion, lethargy, or even coma. In some cases, people suffer from hyperthermia may also have an extremely high body temperature without the ability to sweat.
Measuring body temperature: A thermometer is used to measure a person's body temperature. The thermometer should be cleaned with warm soapy water or rubbing alcohol before and after using. If a person is using a glass thermometer, he/she should shake the thermometer until it reads 95 degrees Fahrenheit or less. The temperature can be taken in the mouth, rectum, ear, or under the arm.
To take a person's temperature by mouth, place the thermometer under the tongue and close the mouth for three minutes.
Body temperature may also be measured with a rectal thermometer. This method is typically used for infants and small children who cannot safely hold thermometers in their mouths. Petroleum jelly should be applied to the bulb of the thermometer. It should then be inserted about one-half to one inch into the child's anal canal. The thermometer is then removed after three minutes.
Body temperature may also be measured by placing a thermometer under the armpit for five minutes. However, this is considered the least accurate method.
A special ear thermometer may also be used. The digital device works by detecting infrared radiation from the ear drum.
When to visit a doctor: If a baby younger than 12 months old has a temperature higher than 100 degrees, a healthcare provider should be consulted immediately. Adults and children who have temperatures higher than 102 degrees that are not responding to medications, such as ibuprofen (Motrin©, Advil©), aspirin, or acetaminophen (Tylenol©), should visit their doctors.
A doctor can easily identify a fever after taking a person's body temperature with a thermometer. However, because it is a symptom of an underlying medical condition, the cause must be identified in order to treat the patient. During a physical examination, a healthcare provider will take a careful medical and social history to determine the underlying cause. If a patient is taking a medication that is known to cause fevers as a side effect, the medication is usually the suspected cause of the fever. Medical tests may also be necessary.
Blood tests may be performed to determine if an infection is causing a fever. Individuals with infections will have a high level of white blood cells, which fight against disease and infection. Samples of the patient's mucus, urine, blood, stools, and/or cerebrospinal fluid may also be taken to determine if an infection is present.
General: People who have fevers may experience complications. However, complications are usually the result of the underlying cause of the fever, such as an infection.
Dehydration: Although dehydration is not a direct complication of a fever, it may occur if a person has an infection and experiences diarrhea and vomiting. In such cases, the body loses fluids and electrolytes. Therefore, people who are vomiting or have diarrhea are encouraged to drink plenty of water. Patients may also benefit from drinks that contain electrolytes, including Pediatric Electrolyte©, Pedialyte©, or Enfalyte©. Individuals should avoid diuretics, such as caffeine, because they worsen symptoms of dehydration.
Febrile seizure: A febrile seizure occurs when an infant or young child develops a seizure or convulsions when he/she has a fever higher than 102 degrees Fahrenheit. Most febrile seizures are caused by viral upper respiratory infections, ear infections, or roseola. Symptoms may include shaking or jerking of the arms or legs, fixed stare, eyes rolling back, heavy breathing, drooling, and bluish skin. Patients who experience any of these symptoms should be taken to the emergency department of a nearby hospital immediately.
Shock: If a person with hyperthermia does not seek medical treatment, the condition may progress to heatstroke. One complication of heatstroke is shock, which occurs when the body does not receive enough blood. Without immediate treatment, the organs may become damaged. In severe cases, heatstroke may result in coma or death if the patient is not treated.
Systemic infections: If an infection is causing a fever and the person does not seek treatment, the infection may enter the bloodstream and spread to other areas of the body. If vital organs, such as the heart, lungs, or kidneys, become infected, it may lead to organ damage.
General: Patients should take acetaminophen, aspirin, or nonsteroidal anti-inflammatory drugs (NSAIDs) and drink cool fluids to help reduce a fever. Although these do not treat the underlying cause of fever, they will minimize symptoms until the underlying cause is effectively treated. Treatment depends on the underlying cause. If it is suspected that the fever is a side effect of medication, a doctor may recommend a different dose or medication. However, individuals should not change their medications or doses unless they talk with their doctors first.
Cool compress: A cool compress may be applied to affected areas of the skin to help reduce symptoms of a fever.
Cool liquids: Drinking cool liquids may help relieve symptoms of fever. Fluids, such as water or drinks that contain electrolytes, including Pediatric Electrolyte©, Pedialyte©, or Enfalyte©, are often recommended because they also help prevent dehydration. However, drinking cool fluids does not treat the underlying cause of the fever.
Sponge bath: A five- to 10-minute sponge bath of lukewarm water may help bring a high temperature down. This cools the skin and may help reduce the body's internal temperature. A sponge bath is most effective if it is used shortly after a dosage of acetaminophen or ibuprofen is given because the medication can work to keep the fever down after the bath takes effect.
Children with fevers who shiver during a bath should be removed from the bath and dried. In such cases, the shivering raises the body's internal temperature because shaking muscles generate heat. If the fever does not improve or the child experiences symptoms of a febrile seizure, seek immediate medical care.
Acetaminophen, aspirin, or nonsteroidal anti-inflammatory drugs (NSAIDs): Patients who have fevers may take acetaminophen, aspirin, acetaminophen (Tylenol©), or nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen (Motrin©, Advil©), to reduce a fever before treatment is started. These medications are only recommended for the treatment of fevers that are higher than 102 degrees Fahrenheit.
Avoid aspirin in children because it may cause serious side effects, including Reye's syndrome, a life-threatening condition that causes brain inflammation and vomiting.
Antimicrobials: Medications called antimicrobials are used to treat infections, a common cause of fevers. Antibiotics are used to treat bacterial infections, anti-fungals are used to treat fungal infections, antivirals are used to treat viral infections, and anti-parasitics are used to treat parasitic infections. The exact type, dose, and duration of treatment depend on the type and severity of the infection, as well as the patient's age and overall health.
Unclear or conflicting scientific evidence:
Bupleurum: Chinese studies have suggested that bupleurum may be helpful for reducing fever. However, additional study is needed to draw a firm conclusion about safety and effectiveness. In traditional Chinese medicine, bupleurum is often used in combination with other herbs.
Avoid if allergic or hypersensitive to bupleurum, Apiaceae or Umbelliferae (carrot) families, snakeroot, cow parsnip, or poison hemlock. Use cautiously if operating motor vehicles or hazardous machinery. Use cautiously with low blood pressure, diabetes, or edema. Use cautiously with a history of bleeding, hemostatic disorders, or drug-related hemostatic disorders. Use cautiously if taking blood thinners. Avoid if pregnant or breastfeeding.
Clove: Clove is commonly used as a fragrant or flavoring agent. There is a risk of blindness if it comes in contact with the eyes. Clove oil (eugenol) has been used for its analgesic (pain-relieving), local anesthetic, anti-inflammatory, and antibacterial effects. Early studies suggest that clove may lower fever, but reliable human studies are currently unavailable.
Avoid if allergic to clove, eugenol, or some licorice products or tobacco (clove cigarette) products. Use cautiously if allergic to Balsam of Peru. Avoid with a history of seizures, stroke, or liver damage. Use cautiously if taking medications that treat diabetes. Use cautiously with diabetes, low blood sugar levels, bleeding problems, or impotence. 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.
Traditional or theoretical uses lacking sufficient evidence:
Aconite: The aconite plant grows in rocky areas. It is often found in the mountainous woodlands of many parts of Europe, especially France, Austria, Germany, and Denmark. It has been suggested that aconite may help reduce the symptoms of fevers. Homeopaths often prescribe aconite preparations at the start of a fever. However, studies are currently lacking in this area.
Aconite is highly toxic and is not safe for human consumption. Avoid with heart disease, irregular heartbeat, hemodynamic instability (abnormal blood flow), or gastrointestinal disorders (such as ulcers, reflux esophagitis, ulcerative colitis, spastic colitis, or diverticulosis). Use cautiously with diabetes or suicidal tendencies. Avoid if younger than 18 years old due to a lack of safety evidence. Avoid if pregnant or breastfeeding.
Agrimony: Agrimony was one of the most famous vulnerary herbs used by the Anglo-Saxons. It has been shown to have anti-inflammatory and diuretic properties. It has been suggested, but not scientifically proven, that agrimony may help reduce fever.
Avoid if allergic to agrimony or related species. When used as recommended, agrimony is considered to be safe. Use cautiously with bleeding disorders. Use cautiously if taking drugs that increase the risk of bleeding or blood pressure-lowering agents. Avoid with diarrhea caused by an underlying illness. Avoid if pregnant or breastfeeding due to a lack of safety evidence.
Licorice: Licorice is harvested from the root and dried rhizomes of the low-growing shrub Glycyrrhiza glabra. Historically, licorice has been used to reduce fever. Some cultures have made a tea out of the licorice root to reduce a person's body temperature. However, until studies are performed in humans, it remains unknown if licorice can effectively reduce fevers.
Avoid if allergic to licorice, any component of licorice, or any member of the Fabaceae (Leguminosae) plant family. Avoid with congestive heart failure, coronary heart disease, kidney disease, liver disease, fluid retention, high blood pressure, or hormonal abnormalities. Avoid if taking diuretics. Licorice may 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 in women.
Rhubarb: Rhubarb is an herb that is commonly used in traditional Chinese medicine (TCM). Traditionally, rhubarb has been used to treat fever. Until studies are performed, it remains unknown if rhubarb can help reduce fevers in humans.
Avoid if allergic to rhubarb, its constituents, or related plants from the Polygonaceae family. Avoid using rhubarb for more than two weeks. Avoid with atony (lack of muscle tone), colitis, Crohn's disease, dehydration with electrolyte depletion, diarrhea, hemorrhoids, insufficient liver function, intestinal obstruction, ileus, irritable bowel syndrome, menstruation, pre-eclampsia, renal disorders, ulcerative colitis, and urinary problems. Avoid handling rhubarb leaves, as they may cause contact dermatitis. Avoid rhubarb in children younger than 12 years old due to water depletion. Use cautiously with bleeding disorders, cardiac conditions, constipation, history of kidney stones, or thin or brittle bones. Use cautiously if taking anticoagulants, anti-psychotic drugs, or oral drugs, herbs, or supplements (including calcium, iron, and zinc). Avoid if pregnant or breastfeeding.
Valerian is an herb native to Europe and Asia. Today, the herb grows in most parts of the world. It is unclear if valerian can help treat fevers. Studies have not been performed to determine if this is a safe and effective fever treatment.
Use cautiously if allergic to valerian or other members of the Valerianaceae
family. Use cautiously with livers disorders. Use cautiously two weeks before surgery. Avoid if driving or operating heavy machinery, as it may cause drowsiness. Avoid if pregnant or breastfeeding.
People can take precautions to avoid contracting infections that may cause fevers. Individuals should regularly wash their hands with soap and warm water. This is especially important after using the bathroom, before eating food, and after touching objects that may contain disease-causing germs. Avoiding close contact with people who have contagious illnesses may also help reduce the risk of contacting infections. Patients are also encouraged to talk with their doctors about recommended immunizations, such as the flu shot.
Individuals should minimize exposure to ultraviolet light and use sunblock when they are exposed to sunlight for prolonged periods of time. This helps reduce the risk of sunburn, which may cause fevers.
This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).
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