Sweat allergy

definition

The sweat allergy (also called "cholinergic urticaria") is not an allergy in the strict sense, as there is no reaction of the own antibodies, which is the body's immune system, to foreign substances. Rather, it is due to the inability to compensate for strong stimuli and shifts in the pH value into acidity. It is therefore a so-called pseudo-allergy, which includes sun allergies, for example. The fact that taking antiallergic medication can still help relieve symptoms is due to the molecules released: These are similar or even the same in a real allergy and a pseudo-allergy.

You might also be interested in: What is an allergy anyway?

causes

Sweat is supposed to cool the skin during exertion, but also makes the skin surface acidic as a side effect. The pH of the skin is therefore lower. This irritates the skin over a large area - even if it is initially not noticed. Since the stimulus cannot be removed, the immune system responds with the release of inflammatory mediators. This immune system reaction occurs whenever the body suspects an injury or a potentially injurious situation: the constant acidic stimulus on the skin is also below it. The inflammation mediators are released more precisely via the so-called mast cells. These are activated and then release the corresponding messenger substances. As a result, the typical allergic signs appear, i.e. increased sensitivity to pain or itching, as well as overheating, redness and swelling due to the increased blood flow. The mechanism for activating the mast cells is important for the distinction between a sweat allergy and a real allergy. This is not done by immune cells, but by an external physical stimulus.

You can find more information on the topic here: Itching of the skin - these are the causes

diagnosis

For the diagnosis of allergies, the so-called prick test is usually used, in which allergens that play a role in the allergy reaction are applied to the skin and the skin surface is then lightly scratched in order to provoke a possible local reaction to the allergen. Since the “allergen” in cholinergic urticaria is one's own sweat, a provocation test can only be carried out by sweating, for example on a treadmill or something similar. Often, however, a provocation test can be dispensed with in milder cases, as it has no effect on the mostly symptomatic treatment.

Concomitant symptoms

The symptoms of a sweat allergy are almost indistinguishable from a skin reaction of a real allergy: Here too, those affected usually notice red, warm, itchy and sensitive skin. The itchy wheals, which then often form due to sweat, are particularly typical of the sweat allergy and thus also give the name of the technical expression "cholinergic urticaria". Urticaria describes the formation of wheals on the skin and is also known as hives. The symptoms are typical when they occur in connection with sweat, e.g. on warm days or during exercise.

This is what the rash looks like

The skin reaction that typically occurs with an allergy are so-called wheals, i.e. reddish or white-looking raised areas of the skin. These are usually very clearly delineated from healthy skin, but can occur confluent if the affected skin area is larger. This skin reaction is also referred to as hives.

The medical term for hives is urticaria, which is why a sweat allergy is also referred to as cholinergic urticaria, even if the sweat allergy is not an allergy in the actual sense, but a so-called pseudo-allergy. An allergic urticaria occurs when there is contact with the allergy-causing substance, i.e. sweat. In order to establish a diagnosis, it can therefore be helpful to locate the places where the hives are visible and to associate them with the parts of the body that are typically sweaty.

Read more on the subject at: Hives

treatment

Even if the causal mechanism of a pseudo-allergy differs from that of a real allergy, both usually lead to the same effect, namely the release of inflammatory molecules. This includes above all histamine, and leukotrienes and prostaglandins, for example, are also involved in the reaction. These molecules then provide the visible skin reaction in the event of a sweat allergy. Symptom relief can therefore be obtained by taking conventional antihistamines.

Read more on the topic: Antihistamines

The drug ketotifen, which is also used to treat many other allergic reactions, has proven particularly effective in chronic urticaria. Those who are keen to experiment can try to neutralize the acidic environment on the skin with baking soda dissolved in water. A spray bottle with a solution of water and baking soda can provide quick relief. It should be noted that an excessively alkaline (i.e. basic) environment is also irritating to the skin - so don't overdo it!
In addition to drug therapy, as is the case with almost all diseases, there is still the appropriate adjustment of lifestyle in order to prevent outbreaks of sweat allergy. This includes, for example, avoiding alcohol, as it increases the level of histamine in the blood by blocking histamine-degrading enzymes. Avoiding or reducing foods containing histamine can also help. Foods containing histamine include meat, cheese, black tea and hot spices. As with many other complaints, it is also true of a sweat allergy that it is also improved by reducing stress.

Read more about the therapy of allergies in general at: Therapy for an allergy

Sweat allergy on the foot

A sweat allergy on the feet can reduce the quality of life, especially in summer or when exercising. Here you should first pay attention to the most breathable footwear possible, but completely closed shoes should be avoided. If this does not sufficiently alleviate the symptoms, a sweat-blocking deodorant can help (attention: these deodorants usually contain aluminum!). A cool foot bath with baking soda as a bath additive also usually alleviates hives. As always, the last option is drug treatment with antihistamines.

You might also be interested in: Sweaty feet.

Sweat allergy in the armpits

There are naturally more sweat glands in the armpits than in other parts of the body. That is why they are logically prone to develop the symptoms of a sweat allergy, such as a rash. A deodorant that closes the sweat glands at this point can help. A newer treatment method is the removal of the sweat glands with the help of a laser, which is also a method for excessive sweating, for example.

Find out more about the topic: Remove sweat glands - when does it make sense?

Sweat allergy on the scalp

A sweat allergy on the scalp is often more difficult to diagnose because the scalp hair makes it difficult to diagnose the typical rash. However, other indications of a sweat allergy on the scalp can also indicate, for example, if the symptoms increase when a head covering is worn and the person concerned sweats more on the head as a result.

You might also be interested in this topic: Sweating on the head- what to do about it

Sweat allergy on the face

The itchy wheals can also be felt on the face when sweating. Since the hives here are quickly visible to everyone, the suffering of those affected is usually very high. Taking an antihistamine is therefore probably the easiest and most effective way. Most active ingredients of this type are available in pharmacies without a prescription, but the pharmacist should be asked about possible side effects and interactions with other drugs. In addition, cold water can acutely reduce swelling and relieve itching. A doctor can be consulted if the symptoms are severe.

Duration and forecast

Anyone with a pseudo-allergy should expect that it will cause symptoms for life. The cause of a pseudo-allergy is likely to be genetic. The fact that some people have a pseudo-allergy and others don't is probably due to the nature of the mast cells: If these are unstable and easier to activate, a pseudo-allergy is more likely to develop. A desensitization, as it is carried out with real allergies, unfortunately does not work with pseudoallergy, since the cause is not the hypersensitive immune system. Long-term relief is therefore most likely to come from lifestyle adjustments.

Difference to neurodermatitis

Atopic dermatitis is a chronic skin disease in which itchy rashes, typically in the crooks of the arms and the hollow of the knees, have usually appeared since childhood. This is usually accompanied by hypersensitive skin. Atopic dermatitis can appear similar to the rash in a sweat allergy.

However, the two diseases usually differ in their occurrence, since neurodermatitis is not suddenly triggered by sweat or warm temperatures, but only worsens the existing symptoms. In addition, neurodermatitis is usually accompanied by a number of other skin characteristics that indicate a general excessive sensitivity. A final diagnosis, also with regard to the distinction between these two clinical pictures, should be made by the dermatologist due to the risk of confusion.

Read more on the topic: Neurodermatitis