What is cholinergic urticaria?
Cholinergic urticaria is a common chronic inducible urticaria caused by sweating. It is sometimes known as heat stroke. Cold hives present with very small (1 to 4 mm) bumps surrounded by bright red rashes. Cholinergic urticaria is also known as cholinergic angioedema urticaria and heat stroke.
Symptoms in cholinergic urticaria
If you are experiencing UC, you may have:
- Hives (small raised bumps on the skin)
- Redness around the bumps
These lumps typically develop within the first six minutes of exercise. Your symptoms may get worse over the next 12 to 25 minutes. Although hives can appear on your body, they often start first on your chest and neck. They can then spread to other areas. These bumps can last from a few minutes to about four hours after exercise. You may also experience symptoms unrelated to the surface of your skin. These include:
- Abdominal pain
- Throwing up
UC can also be accompanied by exercise-induced anaphylaxis, a more serious allergic reaction to exercise. Its symptoms can be life-threatening and require immediate medical attention.
- Laboured breathing
- Abdominal pain
If you have an EpiPen, you should give the medicine while you wait for help to arrive.
Causes of cholinergic urticaria
The heat from saunas could trigger cholinergic urticaria. Cholinergic urticaria can occur whenever a person sweats or gets too hot. The following events or situations can cause a person to develop cholinergic urticaria:
- Hot baths
- Sit in a sauna or hot tub
- Be in a warm room
- Exposure to hot weather
- Running a fever
- Being angry or upset
- Eating spicy food
Experts believe that these situations raise a being’s body temperature and cause the body to release histamine, a compound that the body tends to release in response to injury. This compound causes some people to develop cholinergic urticaria.
Diagnosis of cholinergic urticaria
If you notice that your skin becomes red, itchy, and blotchy when you are hot or if it takes a few minutes to exercise, see your doctor. A dermatologist (skin specialist) or allergist can also diagnose UC. To diagnose it:
- Your doctor will ask what your hives look like when you get them and how long they last to rule out other causes, such as the foods you eat.
- You may be asked to run or ride an exercise bike for about 15 minutes to see if you have a flare while sweating.
- You may be given an injection of methacholine, a medicine that shrinks the airways, to make the bumps appear.
Who gets cholinergic urticaria?
People who are most likely to get cholinergic urticaria to include:
- Those who already have chronic generalized urticaria
- People with asthma, rhinitis, and atopic dermatitis (eczema)
It occurs in both men and women but is more common in men than women. The condition tends to first appear in people between the ages of 10 and 30 and persists for several years before it becomes less severe or disappears completely. The natural sequence of cholinergic urticaria is quite variable, with most patients experiencing slow resolve over several years.
Cholinergic urticaria treatment
Once the cause of the rash is identified, it is possible to avoid situations that trigger it. However, in many cases it is difficult to stop sweating, especially in hot weather, and if exercise is part of the daily routine. Sometimes a quick cooldown can prevent an attack. For most patients, regular administration of an oral antihistamine such as cetirizine can help prevent the condition from developing. Beta-blockers like propranolol have also been stated to be helpful.
One of the easiest ways to prevent cholinergic urticaria is to avoid triggering activities. People who experience cholinergic urticaria should avoid exercises that cause excessive sweating or heat. Similarly, they should also avoid situations or activities that make a person warm. This is particularly true during the summer months.
A doctor will likely prescribe antihistamines to help prevent allergic reactions. These medications will help prevent a person’s body from overreacting to triggers. Other medication options include:
- Sweat reducers
For those who experience anaphylaxis during exercise, a doctor will likely prescribe an EpiPen. A person may also want to find a training partner to help them in an emergency.