Hives: What It Is, Causes, and How It Manifests

The skin swells with itchy bumps or spots of various shapes and sizes — this is what hives look like. About one in three people has had it at least once in their life, and in most cases the rash improves within a few days. Below — what happens on the skin, which causes are named, and by which signs it is time to see a doctor.

What hives are and how they look

Hives (urticaria) is a group of diseases characterized by itchy welts and/or angioedema. A welt is a flatly raised area of skin resembling a nettle sting mark: pink or red, of various shapes and sizes. The rash may stay in one area or spread across the body, and may feel like itching, burning, or tingling.

The shade depends on the baseline skin color: on light skin the welts are pink or red, on brown and dark skin they are harder to notice — sometimes they look like swollen areas of the same tone. Usually such a rash improves within a few days.

Causes of hives: allergy, stress, and other factors

The key cells here are mast cells, which store histamine; when they are activated, histamine is released into the tissues, and the skin responds with a welt. The most common cause is an allergic reaction to a medication or food, and people with other allergies are affected more often. Other causes are infections and stress. Parasites as a cause of chronic hives are rare.

Types: acute and chronic hives

By duration, acute and chronic forms are distinguished. Acute spontaneous hives — welts and/or angioedema lasting less than 6 weeks, chronic — more than 6 weeks. Chronic is divided into spontaneous and inducible, when the rash is triggered by physical stimuli: cold, heat, vibration, pressure. One person may have several forms at once; delayed pressure hives manifests as swelling at the site of pressure several hours after exposure.

Stress is named as one of the causes of hives; it is not distinguished as a separate form "nervous hives" in reference materials.

Adults are affected more often than children, and a quarter of all hives cases are chronic.

Where the rash appears

The rash can appear anywhere on the body — in one area or all over the body. Angioedema is sometimes the only symptom.

Is hives contagious

Hives is an allergic reaction of the body or a manifestation of a disease; its causes are medications, foods, infections, and stress.

Diagnosis, complications, and when to see a doctor

The cause is assessed by a doctor. In rare cases, hives is accompanied by dangerous swelling of the airways, which makes it hard to breathe — this is an emergency.

A routine visit to a doctor is needed if the welts do not improve within 2 days, the rash spreads, returns again, if there is a high fever and poor general condition, swelling under the skin, or if it concerns a child and you are worried. Chronic hives significantly affects quality of life — in terms of the strength of this impact it is compared with psoriasis and coronary heart disease.

• the rash lasts longer than two days or involves new areas;
• the welts return in waves, and there is a link to a medication or food;
• a dense swelling has appeared under the skin — angioedema is possible;
• fever has risen and general condition has worsened;
• it concerns a child, and the condition raises questions for you.

Hives by itself is not a reason to call an ambulance. Call 103 or 112 if the lips, mouth, throat, or tongue suddenly swell; breathing becomes rapid, wheezing appears, or there is a feeling of shortness of breath or suffocation; the throat tightens and it is hard to swallow; the skin, tongue, or lips have turned blue, gray, or pale — on dark skin this is more noticeable on the palms and soles.

The material is for reference: it describes signs and causes but does not replace a doctor's consultation, who sees the skin and knows the full history.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer