Antazoline is a so-called antihistamine that is effective against allergic reactions. It is usually used in combination with a sympathetic stimulant. Antazolin is mainly used as eye drops for allergic conjunctivitis, which can occur for example in hay fever.


The messenger substance histamine is released by mast cells in increased quantities, especially in inflammatory processes and allergies. Mast cells are white blood cells and belong to the body’s own defence system. After binding to various docking sites, so-called histamine receptors, on surrounding cells, typical allergic reactions occur.

These manifest themselves, for example, in the dilation of the vessels, which leads to increased blood circulation and thus to warming and reddening of the respective area. Furthermore, the permeability of the vessels increases, the flow of tears increases, the eyes swell and itch. Antazoline also binds to certain histamine receptors (H1), but without triggering a reaction. The binding sites for histamine are then blocked and the allergic reaction is stopped.

Side effects

Since Antazoline is mainly used as eye drops only at the affected area, most of the active ingredient does not enter the bloodstream. Therefore, side effects outside the affected area are very rare and the drug is generally very well tolerated. There may be an irritation or hypersensitivity reaction in the eye, combined with a burning sensation in the eye.

The most common side effects occur with combined drugs, such as Tetryzolin. Dry eyes, blurred vision and pupil dilation are particularly noticeable. These eye drops should not be used in the case of preexisting glaucoma, as an acute attack can occur. The drug should also not be used in children under 2 years of age.

Eye drops

The most common form of application of Antazoline are eye drops, which are used especially in cases of allergic conjunctivitis. The lower eyelid is pulled slightly forward and the eye drops are dropped directly into the conjunctival sac. Care should be taken to ensure that the tip of the dropper does not come into contact with the eye.

To avoid further irritation of the eye and contamination of both the eye and the dropper. As the mucous membrane at this point is very thin and well supplied with blood, the active ingredient can be absorbed quickly. This leads to a rapid onset of action. The eye drops usually consist of a combination of two active ingredients. In most cases these are antazoline with anti-allergic effect and tetryzoline with symathomimetic effect.


The abbreviation HCL stands for hydrochloride (or hydrogen chloride) and is better known as hydrochloric acid. In their chemical structure, many drugs are present as bases. In order to make them more water-soluble, they are therefore mixed with acids and used as hydrochlorides.

In this way medicines, such as eye drops, can be brought into a liquid form as an aqueous solution. In this case, the substances are then no longer called tetryzoline but tetryzoline hydrochloride. This improves the administration and stability of the drugs.