Berlin  - Vaccinations can alleviate the symptoms of hay fever when conventional methods such as nasal sprays, eye drops and antihistamines fail, according to Germany's Berlin-based Professional Association of Dermatologists.

This form of treatment is called immunotherapy and should be initiated weeks in advance of pollination.

Those who are allergic to the pollen of the hazel and alder trees, which blossom in early spring, should begin a course of immunotherapy in autumn.

For grass allergies, on the other hand, there is still time to begin a course this year as pollination in the northern hemisphere begins in May.

The association says allergy sufferers have a choice between three types of therapy. In the first form, sufferers receive a course of injections of the allergen under their skin in ever increasing concentrations.

This method allows the body's immune system to become less sensitive to the allergen and can help ease the symptoms in the first season of use.

A full course of injections takes three years to complete and its effects last about 10 years. There is also evidence to suggest that this form of therapy can prevent development of allergic asthma, according to dermatologist and allergist Kerstin Jung.

In the second form of therapy, the patient places drops of the vaccine on their tongue. However, doctors say it can be difficult to judge the correct dosage with this method.

The third form consists of vaccine tablets that the patient administers under their tongue. This can lead to some uncomfortable itching and swelling in the mouth in the first few days of treatment.

Vaccine tablets are very suited to patients who don't have enough time to make regular appointments for injections. (dpa)