Effect
The active substance Dimetinden contained in Fenistil® drops weakens the effect of the Histamine in the body. Histamine plays an important role in many processes in the body, for example in defensive reactions against foreign substances. It dilates blood vessels and increases the permeability of the vessel wall.
As a result, the irritated skin area appears reddened and overheated and swelling occurs. It also causes itching or pain in the affected area. This is a useful defensive reaction in the case of an insect bite, for example.
In the case of an allergy, however, there is a hypersensitivity to substances that are actually harmless. Here histamine also plays an important role. Histamine can also cause the typical swelling, overheating and reddening in allergies. The swelling of the nose and throat area is also caused by histamine.By attenuating the effect of histamine, Fenistil® drops thus relieve the symptoms of allergy. They also help to relieve the symptoms of insect bites and hives.
Side effect
Like any drug, Fenistil® drops are not free of side effects. As described above, fatigue is very common. This effect is based on the above described effect as an “antihistamine”.
Conversely, nervousness or excitement may rarely occur after taking Fenistil® drops. Even less frequently, patients complain of headaches or dizziness. The dimetinden contained in Fenistil® drops as an active ingredient not only binds to histamine receptors.
Dimetinden also blocks so-called muscarinergic acetylcholine receptors. These receptors are widespread in the body and control, for example, gastrointestinal activity or salivary flow. For this reason, Fenistil® drops can in rare cases lead to dry mouth or gastrointestinal complaints.
These rare side effects occur in one to ten treated patients under 10,000. Even though Dimetinden is actually used against allergies, the body can become sensitized to the active ingredient. In this case the treated person becomes allergic to the active ingredient and a potentially dangerous anaphylactic shock occurs after ingestion. However, this will probably only happen in exceptional cases.
