How does hypersensitivity affect immune responses

Allergy medication - keeping an eye on the immune system

Where allergy drugs start

A starting point for many allergy drugs is the messenger substance histamine, which so-called mast cells release in the course of an allergic reaction. Histamine plays a key role in mediating allergic reactions. It ensures, for example, that the blood vessels expand, the mucous membranes swell and more mucus is produced in the airways. Special allergy medication can, for example, slow down the release of histamine or block its effect.

Other active ingredients directly suppress the symptoms that occur, for example a runny nose. In the case of more severe symptoms, attempts are made to suppress the immune system's defense reactions with cortisone.

Allergic reaction and its inhibition


In the case of asthma or an allergic runny nose, triggered for example by a pollen allergy, it is possible to prevent the outbreak of the allergy. Suitable for this Mast cell stabilizers (for example cromoglicic acid, nedocromil). These active ingredients ensure that the mast cells are stabilized and cannot release any inflammatory substances (histamine). However, if the allergic reaction is already underway, these active ingredients can no longer help.

It therefore makes sense to start using mast cell stabilizers about two weeks before the expected allergen contact (pollen count!). With regular use (four times a day), mild symptoms such as itching with hay fever or food allergies can be prevented in advance.

Mast cell stabilizers come in the form of eye drops, inhalation sprays, and nasal sprays (but these have a weaker effect on nasal symptoms than antihistamines and topical glucocorticosteroids). Because they are well tolerated, they are also suitable for children, pregnant and breastfeeding women.

To block

H1 antihistamines (Antihistamines) block histamine receptors in cells of the skin and mucous membranes and thus inhibit the effect of histamine that has already been released. The histamine released from the mast cells can no longer bind to the receptors - the allergic symptoms do not occur.

Antihistamines are suitable for the treatment of allergic rhinitis, conjunctivitis and skin reactions such as itching or hives (urticaria). They are used, for example, for hay fever, insect venom allergy and drug allergies. The active ingredients are available on the one hand as tablets and drops for ingestion, on the other hand as locally applicable allergy medication in the form of eye drops, nasal sprays and ointments.

The oral H1 antihistamines first generation (such as Clemastin, Dimetinden) can cross the blood-brain barrier and thus have a sedating effect in the central nervous system - the drugs make you tired, reduce performance and motor skills. This is why some of these preparations are also used as sleep aids. Side effects such as headache, dizziness or dry mouth occur more frequently.

Newer H1 antihistamines the second generation (such as loratidine, cetirizine, azelastine, fexofenadine) are difficult to cross the blood-brain barrier and therefore have little or no sedating properties - however, reduced responsiveness is always possible. Second generation antihistamines are the preferred allergy drugs today.

Swelling of the mucous membranes

Decongestant preparations in the form of eye drops and nasal sprays only work against the symptoms, not against the allergy itself. In the case of severe symptoms, they should be used as a supplement and not longer than a week. Otherwise the mucous membranes will dry out, which is harmful in the long term and can even exacerbate allergic complaints.

Slowing down the immune response

Stronger asthmatic complaints and hay fever go well with cortisone-Treat preparations. Local dosage forms such as eye drops, nasal sprays, ointments or inhalation sprays have relatively few side effects. Cortisone tablets are only given by allergists over a longer period of time if local cortisone preparations do not provide sufficient help. In the long run, cortisone inhibits inflammation as well as the immune system, which can promote infections and wound healing disorders.

Overcoming shock

If the allergic reaction increases to circulatory failure and respiratory arrest (anaphylactic shock), only emergency medical treatment helps, including with adrenalinegiven intravenously. The hormone causes the spasmodically constricted bronchial tubes to widen, the sagging blood pressure rises again and the heart is strengthened.

Seek advice

Many allergy medications do not require a prescription and are therefore freely available in pharmacies. Nevertheless, every allergy sufferer should ask his doctor or pharmacist for advice on which sprays, drops or tablets are useful in his specific case.

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