What is Cholinergic Urticaria?
Cholinergic urticaria is a hypersensitive response in the skin brought on by a physical stimulus. A passive or active increase of the body’s temperature or the excessive sweating can bring on this particular type of urticaria. There are four types of cholinergic urticaria, each one with its own particularities: in the first sub-types, there is also occlusion of the pores; in the second, the patient presents reduced sweating in the entire body; in the third, there is a clear allergy to sweating; the last type is idiopathic.
The prevalence of cholinergic urticaria is higher in people who have been diagnosed with other types of urticaria and also in people who have suffered from different types of atopic dermatitis or other allergies (asthma, rhinitis or atopic eczema). Rare familial forms have also been encountered in the medical literature. This condition is more common in males than females and it often affects young adults (25-30 years). It was first described in 1924 and the majority of the cases are mild, requiring little or no treatment.
This particular type of urticaria is often described as a heat rash or a scratching sensation, appearing after intense physical exercise, spicy foods or increase in surrounding temperatures. What happens is that the exterior stimulus will have a direct effect on the parasympathetic nervous system and also on the immune system. The main neurotransmitter of the parasympathetic nervous system is acetylcholine and this will cause the appearance of the hives by transmitting the irritation response to the nerve endings in the skin. The immune system will respond as well, by releasing histamines and causing the itching sensation. The hives can be evoked in a controlled manner by using cholinergic agonists, such as methacholine, hence the name of the condition.
Cholinergic Urticaria Symptoms
These are the most common symptoms of cholinergic urticaria:
- Rapid onset
- First symptoms appear shortly after the external stimulus (precipitated by sweating)
- Symptoms last between half an hour and an hour and a half
- Burning or tingling sensation
- Warmth and irritation
- The symptoms presented above precede the actual skin urticaria.
- The skin will present small bumps (1-4 mm diameter) that itch intensely, being surrounded by large flares. Persistent macules can also be encountered in some cases. Sometimes, the bumps or macules can become joined, affecting an extensive area of the skin.
- The lesions are often round but they can take other shapes as well.
- They can fade but the surrounding flare will still be visible for some time. The skin will look red, the color fading gradually until the skin heals.
- Any part of the body can be affected, with the exception of the palms of the hands and soles of the feet. Rarely, the urticaria can affect the axillary region as well.
Additional symptoms include:
- Loss of conscience
- Cramps in the abdomen
- Accelerated intestinal transit
- Excessive salivation
In more severe cases, the patient can also present:
- Liver damage
- Anaphylactoid reactions or anaphylactic shock
- Cardio-respiratory symptoms
Causes of Cholinergic Urticaria
When speaking about the causes that lead to the appearance of cholinergic urticaria, we are actually speaking about the triggering factors or underlying conditions. These are:
- Atopic dermatitis
- Increased sensitivity to sweat
- Abnormal response of the immune system to the skin flora that becomes dissolved in the sweat
- Spicy food is a main trigger factor
- Stress, anxiety and emotions can trigger excessive sweating as well
- Increase in core body temperature (working out, general physical activity). This is actually active heating in a low or moderate ambient temperature.
- Passive heating of the body (sauna, taking hot showers or baths, jacuzzi)
- Chronic urticaria
- Acquired idiopathic generalized hypohidrosis – this is a medical condition in which the sweating levels are reduced and it seems that there is a defect in the junction between nerves and sweat glands.
- Absence of sweating
- Aspirin can trigger cholinergic urticaria as well.
Treatment for Cholinergic Urticaria
These are the most common courses of treatment undertaken for cholinergic urticaria:
- Antihistamines can help with the itchiness
- Leukotriene inhibitors
- Rapid cooling
- Applications of UV light (with extreme caution)
- Rapid desensitization with autologous sweat (this is a choice of treatment for patients who have resistance of other methods of therapy and who also suffer from extreme sensitivity to sweat)
- Diet changes – patients are recommended to refrain from eating hot foods and drinking hot beverages, to stop eating spicy foods or drink alcohol
- Avoiding triggering factors is also a recommendation, especially when it comes to the different activities that might cause a person to sweat (physical exercise, increased temperatures, saunas, hot showers or baths, emotions, stress, anxiety)
- Ketotifen is recommended for patients who suffer from cardio-respiratory symptoms
- Beta blockers have also shown promising results
- Topical creams are recommended for the bumps and macules present on the skin
- Synthetic androgens, such as danazol, have also been indicated
- Steroid pulse therapy with methylprednisolone is recommended in cases of cholinergic urticaria caused by acquired idiopathic generalized hypohidrosis
- Cold water sprays and wet towels can also help.
How long does cholinergic urticaria last?
Cholinergic urticaria, as it was already mentioned has a sudden onset and, after the triggering factor has acted as a direct stimulus, the condition will last up till one hour and a half. It can last as little as half an hour but this depends very much on the triggering factor and whether the stimulus was external or internal. Although the symptoms might disappear quickly, most of the patients declare that this condition has affected their quality of life, forcing them to make certain changes related to their physical activities, occupation and diet. Sexual activity is also affected, especially if the patients have already been diagnosed with sensitivity to sweating or allergy. Psychological support might be necessary in some cases.
Cholinergic Urticaria Pictures
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