Hives (hives): an overview and more

Hives (urticaria) usually start as an itchy red patch of skin and develop into a well-defined, raised scar. It is caused by an abnormal immune response. While this can occur as a result of food or drug allergies, there are often non-allergic causes. Symptoms can come and go quickly, or they can be prolonged. Appearance may be sufficient to make a diagnosis, but allergy tests, exercise, or other tests may be required in chronic cases. Antihistamines are commonly used to treat hives, although H2 blockers, corticosteroids, antidepressants, and asthma medications may also be prescribed.

Get Medical Information / Emily Roberts

Symptoms of hives

Hives can affect people of all ages and can develop anywhere on the body, including the palms of the hands and the soles of the feet.

Hives will look like raised scars (blisters or scars) and will invariably itch, some more than others. They can vary in shape and size and have a well-defined edge. When pressed, the center 'fades' (turns white).

Symptoms are generally mistaken for symptoms of other conditions, but careful attention to these determinants can help distinguish hives.

Most hives are acute and go away on their own, and go away on their own within 24 to 48 hours. Others may take days or weeks before they disappear completely. During this time, the hives usually disappear and reappear. Hives can sometimes be accompanied by deep tissue edema known as angioedema , which most often affects the face, lips, tongue, throat, or eyelids.

Chronic hives can persist for months or even years and can be caused by stress, heat, cold, and other physical factors.

Hives differ from eczema (atopic dermatitis) in that eczema is characterized by dryness, crusting, cracking, oozing, or bleeding. Hives are not usually described in this way.

Hives on the leg.

Causes

Generally speaking, all forms of hives are the result of an abnormal immune response. While allergies are the most common example, this is not the only cause .

Some chronic forms of hives are believed to be caused by an autoimmune response .

Allergy-induced urticaria

Hives caused by allergies occur when the immune system reacts abnormally to a harmless substance and releases a chemical known as histamine into the bloodstream. Histamine is an inflammatory substance that causes allergy symptoms that affect the respiratory system, gastrointestinal tract, and skin.

Common triggers for hives caused by allergies include food (including shellfish, eggs, and nuts), medications (including aspirin and antibiotics) , and insect stings (especially bees and fire ants).

Chronic idiopathic urticaria

Chronic hives are usually idiopathic and can worsen during stress. The exact route of development of the condition is unknown. In some patients, autoantibodies (immune proteins that target the body's own cells) are found in the blood, but these autoantibodies do not necessarily cause disease. Testing for these autoantibodies is generally not recommended because positive results do not diagnose chronic urticaria and do not help with routine treatment.

Although the cause of chronic hives may be different from allergy-induced hives, the effect will be the same (although longer lasting). Women tend to suffer more than men.

In addition to stress, common physical triggers include exposure to cold, heat, sunlight, pressure, vibration, water, and friction. Some types of exercise-induced hives only occur in conjunction with a food allergy. In other words, exercise alone will not trigger a reaction and food alone will not trigger a reaction, but in this form of allergy, eating a certain food (such as wheat) followed by exercise can trigger a reaction.

Other reasons

Infections and diseases such as hepatitis, chronic kidney disease, lymphoma, and any number of autoimmune diseases (including lupus, Hashimoto's thyroiditis, and rheumatoid arthritis) can also present with acute or chronic urticaria.

Diagnostics

Hives can usually be diagnosed by looking at your medical history and the characteristic appearance of the rash. Laboratory tests and imaging are generally not required unless an underlying cause, such as cancer, is suspected.

The severity of the rash can be classified according to an assessment tool called Urticaria Activity Assessment (UAS). To do this, the patient subjectively rates two main symptoms – blisters and itching ( itching ) – on a scale of 0 (low disease activity) to 3 (severe disease activity). A maximum score of 6 often means that the patient needs more treatment, especially if the symptoms are chronic.

If further testing is needed, they may include one of the following:

  • An allergy test may be recommended if you've had a severe hypersensitivity reaction to food, medicine, or an insect bite. The skin test or the specific IgE test are the two most common forms of allergy testing.
  • The stress test is used to confirm that chronic hives are caused by physical stress. This includes applying suspected irritants such as ice, heat, vibration, light, or friction to the skin. Stress tests can also be used.
  • A skin biopsy (taking a tissue sample for laboratory evaluation) is only indicated if the hives do not improve and no other cause can be found. Unless there is an unusual explanation for the blisters, a hive biopsy usually does not reveal anything abnormal.

Watch out

In most cases, acute hives will go away on their own within a few days, and the itching and swelling can be relieved with a cool, wet compress.

The strongest antihistamines are available by prescription.

If antihistamines are sufficient to alleviate the condition, other medications may be added or replaced, especially if the cause is not allergic.

From them:

  • H2 blockers such as Pepcid (famotidine) and Tagamet (cimetidine) can be used in combination with antihistamines to reduce vascular edema.
  • Corticosteroids like prednisone can weaken the immune response and quickly relieve itching and swelling. While this can be beneficial for a few days, it is generally not recommended in the long term due to the potential for serious side effects .
  • Leukotriene modifiers such as Accolate (zafirlukast) and Singulair (montelukast) are commonly used to treat asthma, but are also used off-label to treat certain forms of chronic idiopathic urticaria that have not been improved by antihistamines alone.
  • Doxepin is a tricyclic antidepressant that also acts as a powerful antihistamine when used in low doses.
  • Xolair (omalizumab) is an injectable monoclonal antibody effective in treating chronic forms of hives that are refractory to antihistamines.

Get the word of drug information

While hives can be unsightly and unpleasant, they are usually not serious. However, if they begin to affect your quality of life, ask your healthcare provider for a referral to an allergist who will do tests to determine the cause.

In rare cases, hives can develop as part of a life-threatening allergy known as anaphylaxis . If your hives are accompanied by facial swelling, shortness of breath, heart palpitations, vomiting, and / or confusion, call 911 or have someone drive you to the nearest emergency room. If left untreated, anaphylaxis can lead to shock, coma, heart or respiratory failure, and death.

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