Causes of Hives

Hives, swelling, intense itching and redness: Under a spontaneous urticaria (hives), every fourth person suffers at least once in his life, and 800,000 Germans suffer from the chronic form. The triggers of the often agonizing skin disease are manifold, and in some patients the causative agent is not found at all. What are the differences between the various forms of urticaria?

Acute urticaria

Wheals are dot-like elevations of the skin that occur after insect bites or may be symptoms of allergy or hives. Click to enlarge. In acute urticaria, symptoms do not last longer than six weeks. When hives develop without a provoking external stimulus, it is called acute spontaneous urticaria. More than 90 percent of cases of acute spontaneous urticaria last only a few days to weeks. More common causes include infections, drug intolerances (often antipyretics and antibiotics), and food allergies or intolerances. In any case, there must be a close temporal relationship between, for example, taking a medication and the appearance of the symptoms.

Chronic spontaneous urticaria

If the symptoms of spontaneous urticaria are still present after six weeks, physicians refer to it as chronic spontaneous urticaria. It can occur daily, weekly, or less frequently and can last for years or decades. This can often only be endured by those affected by regularly taking medication. In severe forms, it is worthwhile to thoroughly search for the triggers with the aim of eliminating them. Chronic urticaria is again divided into three groups: About two-thirds of all cases of chronic spontaneous urticaria can be assigned to them. In about one-third of patients, the causative agents remain unfathomable.

  • Intolerance urticaria: Hypersensitivity to food components such as dyes, flavorings, or preservatives. Histamine-rich foods such as aged cheese and sausage can also trigger intolerance urticaria.
  • Infectious urticaria: This refers to the reaction to an inflammation in the body that does not have to cause other symptoms. It is often gastrointestinal and ear, nose and throat or dental root infections.
  • Autoreactive urticaria: intolerance of substances produced by the body.

Chronic inducible urticaria.

This group includes the forms of urticaria in which symptoms occur only after certain stimuli. Here again, they are subdivided into groups: The largest subgroup here is symptomatic dermographism – also called urticaria factitia – which is one of the physical forms of inducible urticaria. Rubbing, scratching or scrubbing leads to wheals, redness and itching within a few seconds or minutes – and only in the exact areas where the skin has been irritated. To be distinguished from symptomatic dermographism is pressure urticaria, in which deep swellings follow hours after the application of pressure and may even be painful in joint areas. In contrast, the superficial wheals do not occur in pressure urticaria.

Other forms of physical urticaria

Cold urticaria is a common form of physical urticaria. Here, the term “cold” describes anything cooler than human skin. The higher the threshold temperature, the temperature that still triggers wheals, the more frequently the patient experiences symptoms. In the course of the disease, the threshold temperature remains relatively stable, but can be lowered by treatment. It is more common in cold countries than in warm countries. For example, cold urticaria can cause the consumption of cold drinks or ice to cause swelling of the throat. Such swelling can result not only in difficulty swallowing, but also in severe shortness of breath. Among the rarer forms of physical urticaria is light urticaria, in which the typical wheals and itching occur after exposure to light, especially sunlight, usually in spring and summer, usually seconds to minutes after light contact. Because clothing does not block all UV rays, wheals may also form on covered parts of the body. Patients often react to only part of the wavelength range.Some react in the visible light range, the others only to UVA or UVB radiation. Another – albeit rare – form of physical urticaria is heat urticaria, in which wheals and itching occur on skin areas that are exposed to heat. If it occurs in warm air or warm water in summer, it can be confused with light urticaria. Cholinergic urticaria is also one of the inducible forms of urticaria and it is quite common. Symptoms develop after the body temperature is raised, for example, by sweating, excitement, or fever. Small pinhead-sized wheals enclosed by a larger redness are typical of this form. After cooling, the wheals disappear without a trace within minutes to hours. More information about hives is available at http://www.nesselsuchtinfo.de.