WHAT IS IT?Urticaria (urtica = nettle) is the medical term for hives or nettle rash. It is a rapidly developing, often intensely itchy rash on the skin, starting with red spots and then progressing to raised, pale patches. The skin lesions may or may not merge into larger, flat patches. Essentially, it involves fluid accumulation in the upper layer of the skin due to dilation of the small capillaries in the skin (the red phase), after which the fluid leaks into the tissues (the pale phase).
One such spot is called a urtica or wheal; the entire condition is called urticaria. This reaction is generally unpleasant, but usually not serious, as the process almost always resolves within a few hours. The initially itchy spots then gradually disappear.
Urticaria is a common skin reaction. A quarter of the population will experience it during their lifetime. The causes vary and the condition occurs at all ages, in both men and women.HOW DOES IT COME ABOUT?There are a thousand and one causes of urticaria. Histamine appears to play a significant role in its development, not only because it dilates blood vessels but also because it causes itching. Besides histamine, other endogenous substances also play a role in the development of hives. These substances are stored in certain "storage sites" (primarily mast cells) present in the skin. They are released from these under the influence of stimuli of various kinds.
Such stimuli can include consuming a medication or food, but also an infection, physical exertion, or the effects of sunlight on the skin. Often, the nature of the stimulus is unknown, and detection is impossible. Normally, the aforementioned stimuli do not trigger a reaction because any adverse effects are neutralized by the body. If this process is less efficient, urticaria can develop. Multiple stimuli can also be present simultaneously.
As far as the triggers are known, they are usually classified into the following groups:
- medications (particularly painkillers, such as aspirin, antibiotics, and X-ray contrast media)
- acute and chronic infections (primarily caused by bacteria and parasites)
- physical stimuli (physical exertion, local pressure on the skin, cold, heat, sunlight)
- food additives (particularly colorants, preservatives, and flavor enhancers)
- food allergies (particularly eggs, shellfish, and fruit)
- allergies to inhaled products (mold spores, animal dander, solvents, formaldehyde)
- insect stings and bites (fleas, mites, lice, mosquitoes, wasps)
- internal diseases (metabolic disorders, hormonal disorders, autoimmune diseases
) - skin contact with certain substances (such as plants, rubber, chemicals, animal proteins, and creams).
Although there is no clear hereditary predisposition, the phenomenon can occur more frequently in certain families than is usual. This is the case, for example, with certain types of urticaria. such as the so-called cold urticaria and sunlight urticaria.WHAT ARE THE PHENOMENA?Urticaria can appear as pinhead-sized, itchy red bumps, dime- to gold-sized pale patches, irregularly bordered, confluent discs, and palm-sized, mobile pale patches. All these slightly raised areas are also called wheals, indicating a thickening of the skin.
There is no particular predilection for location: urticaria occurs equally often on the arms, legs, trunk, and face. If someone is sensitive to local pressure, the wheals are more likely to appear on pressure points caused by clothing; contact urticaria usually affects the hands and face. Urticaria from insect bites is most common on the forearms and lower legs.OTHER FORMS OF URTICARIAThe form of urticaria characterized by smaller, itchy bumps primarily occurs after exertion or emotional stress. This is called exertional urticaria.
A harmless but bothersome variant is urticaria factitia. In this case, itchy, striped bumps develop in response to pressure or rubbing of the skin, which disappear spontaneously after some time. They can even be provoked by writing a blunt object on the back. This phenomenon is therefore also called positive dermographism. This condition occurs to a greater or lesser extent in 3-5% of the population and can be long-lasting. Urticaria factitia is a classic example of a regulatory system that is not entirely in balance. Often, there are multiple underlying causes.
Another specific form of urticaria is the aforementioned cold urticaria. This occurs, for example, while swimming. It can even lead to dangerous situations (drowning) if a more generalized reaction with a drop in blood pressure and loss of consciousness develops.
Cold urticaria can be induced by holding ice cubes on the skin for some time.HOW IS THE DIAGNOSIS MADE?Urticaria is easily recognized by doctors. The doctor will first inquire about common causes when you first present with this problem. Discussing a possible cause together resolves many cases without the need for further investigation.
Only when the condition proves persistent may further investigation be necessary. The nature of this investigation depends partly on the information obtained during questioning, the investigator's investigative skills, and the experience of the examiner. Blood tests can be used to identify a cause in many ways. X-rays, bacterial cultures, urine and fecal tests, allergy tests, and provocation tests can also provide clues to one or another cause. All of this takes considerable time (sometimes several months) before all potential causes are systematically investigated. The importance of a thorough investigation also depends on the extent to which you experience any disruption in your daily activities and your ability to perform your work normally.WHAT IS THE BEST TREATMENT?Medications that block the action of the regulatory substance histamine are often effective. These medications are called antihistamines. In the past, they had an unpleasant side effect for some users, namely drowsiness or sleepiness. Nowadays, there are antihistamines that no longer have this effect.
Children can receive this medication as a liquid; older adults usually receive capsules or tablets. If the skin reaction is expected to subside within a few days, an anti-itch lotion or a shake can also be effective.
Chronic urticaria sometimes requires long-term use of antihistamines or a combination with other medications.WHAT ARE THE OUTLOOK?In most cases, the skin reaction is short-lived (acute urticaria). It can be so brief that the symptoms disappear before anyone even decides to see a doctor. However, some people experience recurring reactions for several days in a row and even persist for weeks or even months (chronic urticaria). In that case, the condition can become very bothersome and require further investigation to identify and, if possible, eliminate the cause. In most cases, however, despite intensive investigation, no cause is ultimately found. |
