Updated: September 29, 2019
Hives are a red, raised, itchy skin rash that appear suddenly, either as a result of the reaction to certain allergens, or for unknown reasons.
It is also known as urticaria, welts, weals, or nettle rash. Usually these causes itching, but may also burn or sting. They can appear anywhere on the body, including the face, lips, tongue, throat, or ears. Hives can change size rapidly and move around, disappearing in one place and reappearing in other places, and may join together to form larger areas known as plaques. They can last for hours, or up to one day before fading. Ordinary hives flare up suddenly. Sometimes hives are developed by direct physical stimulation by environmental forces like heat, cold, and sunlight. When an allergic reaction occurs, the body releases a protein called histamine. The tiny blood vessels known as capillaries leak fluid when histamine is released. The fluid accumulates in the skin and causes a rash. It is not contagious and typically are not associated with long-term or serious complications.
Hives, or urticaria, can be acute or chronic.
It is the most common type where the symptoms last less than 6 weeks. They typically affect the face and neck, fingers, toes, and the genitals of males. However, any part of the body can be affected. The most common causes are certain foods, medications, or infections. Insect bites and internal disease may also be responsible.
It continues for more than 6 weeks. The exact cause is unknown, but it may link to the immune system. Viruses can also trigger hives. In some cases, it may relate to an underlying autoimmune disorder, such as thyroid disease or lupus. Hepatitis, infection, or cancer can also be the cause. It can affect other internal organs such as the lungs, muscles, and gastrointestinal tract. Symptoms include muscle soreness, shortness of breath, vomiting, and diarrhea.
Other types of hives may include:
Hives caused by direct physical stimulation of the skin, such as cold, heat, sun exposure, vibration, pressure, sweating, and exercise are known as physical urticaria. Usually it occur in the area where the skin was stimulated and rarely appear elsewhere. Most of the hives appear within one hour after exposure.
This is a common form of physical urticaria, but can also occur along with other forms of urticaria. In this case hives form after firmly stroking or scratching the skin.
This is similar to hives, but the swelling occurs beneath the skin instead of on the surface. Angioedema develops a deep swelling around the eyes and lips and sometimes of the genitals, hands, and feet. It generally lasts longer than hives. The swelling usually goes away in less than 24 hours. Rarely, angioedema of the throat, tongue, or lungs can block the airways, causing difficulty breathing which may become life threatening.
Swellings, known as wheals, appear as a rash on the skin which are usually pink or red, with different shapes such as an oval or round shape. They can vary in size ranging from a few millimeters to several inches. They can be extremely itchy, and have a red flare around them. The weals usually occur in batches, frequently on the face or the extremities, including the arms, hands, fingers, legs, feet, and toes.
They can appear on just one part of the body, or on several parts.
Symptoms normally disappear within 24 hours, but sometimes another wheal appears as the last one fades. In some cases, hives can continue for several days. People with chronic hives can have symptoms for months or years.
If hives occur with any of the following symptoms, contact your doctor immediately:
If hives are making it difficult to sleep, then it may be necessary to see a physician.
Anaphylaxis is a severe allergic reaction that can affect the whole body and can lead to serious breathing difficulties and a loss of consciousness. It can be fatal if not treated quickly. It is a medical emergency.
Immediate medical attention is needed if the following symptoms occurs:
People with hives need to be alert for further symptoms which could indicate an anaphylactic reaction.
Hives are developed when the body reacts to an allergen and releases a protein called histamine and other chemicals from under the surface of the skin.The histamine and chemicals cause inflammation and fluid accumulation under the skin, causing wheals.
Examples of known triggers include:
Chronic urticaria may start as an autoimmune response, but the cause is unknown.
Diagnosis will depend on the type of urticaria. A patient will likely be referred to a dermatologist and/or an allergy specialist for further investigation when hives become chronic.
In acute urticaria, allergy testing can help to find a specific substance or trigger for the hives reaction. Finding out the specific trigger can help prevent recurrences.
A doctor can diagnose acute urticaria by examining the rash on the skin and considering your medical history. The doctor may refer the patient to an allergy clinic where they test the blood and skin of the patient to find out whether there is an allergy to specific substances, such as chemicals, dust mites, or some food.
The trigger is probably not external if the urticaria continues for more than 6 weeks. So an allergy tests at this point is not recommended. Other test should be done to find out the underlying cause.
The following tests can check for underlying health conditions:
Factors that may worsen the existing urticaria include:
The goal of treating most cases of acute urticaria is to relieve symptoms. Most of the time the condition goes away by itself. The most commonly used oral treatments are antihistamines. It works by opposing the effects of the histamine leaked by mast cells. The main side effect of antihistamines is drowsiness.
Antihistamines, such as cetirizine or fexofenadine, help by blocking the effects of histamines and reducing the rash and stopping the itching. Some are not suitable during pregnancy unless prescribed by a doctor.
Without prescription antihistamines, such as diphenhydramine, and chlorpheniramine are also available. Diphenhydramine should be taken in doses of 25 milligrams and chlorpheniramine should be taken in a dose of 4 milligrams. These can be taken up to three times a day, but because these medications can cause drowsiness, they are often taken at bedtime. Make sure you are fully alert before driving or participating in other activities requiring mental concentration while taking these medicines.
Over the counter medicines such as Loratadine and fexofenadine are antihistamines available that are less likely to cause drowsiness.
Antihistamines that require a prescription include cyproheptadine, which also cause drowsiness. Levocetirizine is a prescription antihistamine that causes little sedation. Sometimes physicians combine these with other types of antihistamines called H2 blockers, such as ranitidine and cimetidine.
The physician will individualize treatment plans that suit to specific patients and modify them depending on the clinical response.
Oral steroids such as prednisone can help severe cases of hives in the short term. Because of their side effects these are not recommended for long term use. Some common side effects of oral steroids include acne, blurred vision, cataracts or glaucoma, easy bruising, difficulty sleeping, high blood pressure, increased appetite and weight gain, increased growth of body hair, insomnia, lower resistance to infection, muscle weakness, nervousness, osteoporosis, stomach irritation or bleeding, sudden mood swings, puffy face, water retention, swelling and worsening of diabetes.
Other treatments that can be used for urticaria include montelukast , ultraviolet radiation, antifungal antibiotics, agents that suppress the immune system, and tricyclic antidepressants such as amitriptyline, nortriptyline and doxepin.
Chronic urticaria can cause long term discomfort, and sometimes complications can occur. Treatment is different than that for acute urticaria.
Dapsone is an antibiotic that can reduce redness and swelling. Omalizumab or Xolair, is a monoclonal antibody injectable drug that blocks immunoglobin E, a substance that plays a role in allergic responses. It can reduce symptoms of chronic idiopathic urticaria. It is a type of hives whose cause is unknown and can last for months or years.
Topical therapies for hives which include creams and lotions that help numb nerve endings and reduce itching are available but are generally ineffective.
Camphor, menthol, diphenhydramine, and pramoxine could be the ingredients in many of these topical medicines. Even a strong prescription cream containg Cortisone, are not very helpful in controlling the itch of hives.
Those with severe symptoms may need to see a specialist. Applying cool compresses may help soothe the itch of a hives rash. Chronic hives can lead to severe discomfort, distress, and possibly depression. Stress can also be a factor which aggravate hives, creating a vicious cycle. Patients who experience symptoms of depression should speak to a doctor.
here are some tips to manage hives while you are getting treatment for hives and swelling to disappear:
Some type of rashes that may look like hives. But they remain stable and do not resolve within 24 hours as hives usually does. This is helpful in distinguishing them from hives. However a biopsy can always be done to make sure the diagnosis.
Most cases of hives are annoying, but not serious, and almost always temporary.