© by aha! Swiss Allergy Center - Info on allergies - Eczema/skin reactions - Urticaria – nettle rash - hand skin with weals which are accompanied by rednessIf the skin itches badly and looks as if the person has touched stinging nettles, it is highly likely to be a case of urticaria. A distinction is made between an acute and a chronic form.

Causes and triggers of urticaria

Acute urticaria

Acute urticaria is frequently triggered by an infection. However, it may also occur as a symptom of an allergy, e.g. a food, insect venom or drug allergy.

Chronic urticaria

Triggers of chronic urticaria are often difficult to identify,  but allergies rarely play a role. Depending on the trigger, a distinction is made between different forms of urticaria, which can additionally be exacerbated by physical or psychological stress as well as strong emotions. Mechanical or physical stimuli or irritants often play a key role as triggers, e.g. temperature difference or scratching. However, chronic urticaria can also appear purely as a result of physical exertion.

Symptoms of urticaria

Urticaria (also known as nettle rash or hives) is a concentration of weals which are usually accompanied by redness of the skin. The weals are swellings of the upper skin layer measuring a few millimetres to a few centimetres.  These skin reactions are accompanied by itching that is often intense and is made even worse by scratching. These symptoms apply to both the acute and chronic form of urticaria.

Acute urticaria

Acute urticaria develops suddenly and lasts just a few hours to days. Depending on the trigger, however, the symptoms may take one or two weeks to disappear.

Chronic urticaria

Urticaria is referred to as chronic when the symptoms last longer than 6 weeks. There may be a few symptom-free days or weeks between episodes.


Acute urticaria

If urticaria of allergic origin is suspected, an allergology workup should be done after the acute episode has subsided. Skin tests and blood tests are available for detecting allergies. A provocation test is sometimes performed to detect reactions to medicines (e.g. painkillers).

Chronic urticaria

As triggers of chronic urticaria are often difficult to identify, the urticaria sufferer should ideally keep a symptom diary for a prolonged period of time. The person’s own observations are an important source of information for the doctor when targeting the treatment.

Therapy and treatment

Acute urticaria

An antihistamine in tablet or drop form is usually sufficient treatment. In some cases, a cortisone preparation may also be used in order to shorten the duration of the urticaria episode. If the skin is badly affected, it is important to avoid irritating the skin by scratching, rubbing or applying pressure. The skin may also be nourished by the additional use of a moisturizing lotion or cream.

Chronic urticaria

Treatment of chronic urticaria requires a lot of patience from the sufferer and the doctor. Often no cause can be found. Treatment primarily focuses on relieving the itching and reducing the weals. Antihistamines are the basis of treatment and these can also be taken at higher doses and for several weeks and months. Additional medicines (mast cell stabilizers, leukotriene receptor antagonists, IgE antibodies, etc.) may be used, depending on the person’s progress.

Foods or food additives rich in histamine cannot trigger urticaria but they can make the symptoms worse. This has to be investigated in the individual case.

Tips and tricks in urticaria

  • Experienced nutritionists can use their expertise to help you change your diet. aha! Swiss Allergy Centre keeps a list of HF/FH certified and experienced nutritionists who have qualified and recognized training and have completed advanced training on the subject of food allergies and intolerances.
  • Relaxation techniques (e.g. autogenic training or progressive muscle relaxation) and other calming measures can provide effective support to individuals experiencing severe mental stress.

Facts and figures

  • Around one in five people will suffer an episode of urticaria at some time in their lives.
  • It mainly affects adults, women twice as commonly as men.

Editors: aha! Swiss Allergy Centre in co-operation with the Scientific Advisory Board. For prevalence figures, see source references.

aha! Swiss Allergy Centre helps

  • aha!shop: other booklets and factsheets provides detailed information and are available in German, French, Italian
  • aha!kinderlager for children with allergies aged between 8 and 12 years
  • aha!jugendcamp for youngsters aged between 13 and 16 years
  • Other education and courses on the subjects "Allergy, asthma, chronic bronchitis", "Anaphylaxis"
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