Diagnosis | Allergic reaction


The diagnosis of an allergic reaction is usually easy to make. Often the affected person can already identify possible triggers himself – for example, watery and itchy eyes after a long walk through blooming meadows and fields. The description of the typical symptoms such as itching, reddening and wheals up to respiratory distress and circulatory reactions usually already leads to the correct diagnosis.

It is then important to identify the exact trigger of the allergic reaction, which is not always easy. For example, an allergic reaction after a certain meal is not necessarily due to a certain food contained in the food. A closer examination of the facts may then become necessary.

Do what?

Depending on the severity of an allergic reaction, it requires different treatment. Slight local reactions to an allergen, which only cause reddening and itching of the skin, usually do not require any therapy and disappear on their own within a short time if the trigger is avoided. Cooling and anti-allergic gels can alleviate the symptoms somewhat.

However, if more severe symptoms occur, which also include systemic reactions, such as shortness of breath, drop in blood pressure, rashes and itching all over the body or extensive swelling, a doctor should be consulted as soon as possible. Clinical monitoring of the affected person must then be ensured in order to be able to react directly to dangerous symptoms such as shortness of breath and drop in blood pressure. Patients are then given anti-inflammatory medication such as prednisolone, which is intended to curb the body’s excessive immune reaction.

Fluid is also administered to stabilize the circulation. When the symptoms have subsided and the patient has recovered, he can go home again. In this context, Vividrin® eye drops are used to treat allergic reactions. Vividrin® Eye Drops is a drug used for the treatment of allergic eye complaints.


The duration of an allergic reaction depends largely on its extent. Local reactions with reddening of the skin, itching and swelling, which are restricted to a rather small part of the body, usually disappear on their own a few hours after the end of contact with the allergen. However, if the allergic reaction is severe and may even require hospitalization, it may take several days to weeks for the body to fully recover. Previous illnesses of the affected person as well as his age also influence how quickly he will recover after a severe allergic reaction. The classic, mild allergic reactions do not usually last long, however, so that complete freedom from symptoms can be expected after a few hours or days.

Differentiation according to localization

Allergic reactions on the skin are the most common manifestation of hypersensitivity. The most common are contact allergies, which are triggered by direct contact of the skin with a certain substance. The body recognizes this substance as foreign and initiates an immune reaction against it.

This is manifested on the skin by redness, wheals and itching. Blisters can also occur. If contact with the triggering substance is broken off, the local reaction usually disappears again within a few hours.

Allergic reactions to mosquito or insect bites are among the most common allergic reactions, as insect venoms are among the most potent allergens. Up to a quarter of the population show increased local reactions to insect bites that go beyond the small bite. Symptoms usually occur shortly after the bite and, like other allergic reactions, can range up to life-threatening respiratory and cardiovascular failure.

These severe complications appear to be more common in allergies to insect bites overall than in other allergies. In these cases a doctor should be consulted immediately. The advantage of allergies to insect venoms is that there is the possibility of so-called hyposensitization.

For this purpose, the insect venom is injected under the skin of the affected person in a highly diluted form. The dose is initially increased with each injection and administered once a week. Later, the patient receives another injection once a month for a period of three to five years.

In this way, a very effective vaccination protection can be achieved, with a success rate of 80-95% depending on the insect venom. This is an optimal way to avoid severe allergic reactions to insect venoms. Allergic reactions can manifest themselves all over the body – including the face.

The mucous membranes of the eyes and nose are particularly often affected by the reaction. The eyes are reddened, begin to water and itch. The nose runs or feels very dry.

The skin of the face can also be affected. Redness, wheals and itching may occur. In the case of allergic reactions caused by contact with a certain substance – for example, a face cream – the symptoms often appear soon after the allergen is applied and do not improve as long as contact with the trigger continues.

However, there are also late reactions to allergenic substances that occur only after a longer period of time. The danger of allergic reactions in the head and neck area is that the respiratory tract of the affected person can swell. This is basically possible with every allergic reaction.

Due to the close proximity, however, this danger is particularly given with allergic reactions in the facial area. If eyes and lips swell and symptoms of shortness of breath occur, a doctor should be consulted as soon as possible. Tattoos can trigger allergic reactions.

The colours used consist of mixtures of substances among which the individual substances are potentially allergenic. Usually the symptoms of the allergic reaction are limited to the tattoo and its immediate surroundings, but if the reaction is pronounced it can also occur over a larger area or even trigger systemic symptoms such as shortness of breath and a drop in blood pressure. Much more frequent, however, is the local allergic reaction, which is noticeable by redness, itching and wheals or blisters on the affected skin areas.

If these symptoms persist, the tattoo should be removed. Other therapies are not promising, as the applied colour remains in the skin and continues to irritate the immune system. Laser therapy can remove a tattoo in several sessions.

An allergic reaction to alcohol is very rare. If typical allergy symptoms occur after the consumption of alcoholic beverages, a certain ingredient of the beverage is usually the cause of the symptoms, but not the alcohol itself. Wine, for example, contains histamine, which is also responsible for the development of the typical symptoms in allergic reactions.

If reddening of the skin, headaches, diarrhoea or similar symptoms occur after drinking wine, this is usually due to histamine intolerance – not an allergic reaction. In beer, the most common allergenic ingredients are malt and hops, wheat, barley and oats. Other alcoholic mixed drinks such as cocktails consist of various alcoholic beverages and juices, each of which, taken separately, can have a potentially allergenic effect.

It is therefore important to pay attention to whether allergy symptoms occur in other contexts than in alcoholic beverages even when these ingredients are consumed. In this way, the allergenic agent can be identified and avoided in the future. In principle, it is possible to have an allergic reaction to the alcohol itself, but allergic reactions to other ingredients of the beverages are much more likely.

If all alcoholic beverages cause the same symptoms, then the alcohol itself could be the cause of the symptoms. An allergy test by a dermatologist may help to find the trigger.