A medication that allows hay fever sufferers to get allergy shots in the form of a pill seems to have lasting benefits, a new study finds.

The drug, called Grazax, is a prescription medication approved in Europe for the treatment of allergies to grass pollen, one of the major triggers of springtime hay fever.

The pill offers an alternative to allergy shots, which are typically recommended when hay fever symptoms cannot be controlled with standard medication. Allergy shots help prevent symptoms by exposing people to small amounts of the substance to which they are allergic, essentially desensitizing the immune system to the allergen.

Allergy shots are typically given weekly at first, followed by monthly injections over several years. The treatment does not cure hay fever but is generally effective at reducing symptoms. However, the inconvenience and discomfort limits patients' willingness to try allergy shots.

Grazax pills, which dissolve under the tongue, contain a small amount of grass-pollen extract. The drug is taken daily, starting several months before the start of the allergy season and continuing for three years thereafter.

In the new study, researchers looked at the medication's long-term effects in patients who had stopped using it after the recommended three years. They found that, compared with patients who had been given a placebo, Grazax users had one-quarter fewer hay fever symptoms one year after stopping the medication.

They also had less need for antihistamines and other allergy medications, according to a report in the Journal of Allergy and Clinical Immunology.

These longer-term findings, the researchers write, support Grazax as a treatment option for people whose hay fever symptoms fail to improve with standard medication.

Dr. Stephen R. Durham, of Imperial College London in the UK, led the study, which was funded by Denmark-based ALK-Abello, the maker of Grazax. Durham and several co-researchers on the study have received research grants and other funds from the drug company.

The findings are based on 257 adults with grass pollen allergies, confirmed through allergy tests. They were randomly assigned to take either Grazax or inactive placebo tablets every day, beginning four to eight months before the next grass pollen season. They continued the therapy for three years.

Over those three years and for one year after stopping the treatment, the patients rated their daily symptoms and allergy medication use.

During the year following treatment, patients in the Grazax group reported a 26 percent reduction in symptoms like congestion and itchy, watery eyes compared with the placebo group. They also had a 29 percent reduction in medication use and gave higher ratings to their quality of life.

Those differences were similar to those seen during the three years of active treatment, according to the researchers.

During the last year on treatment, 15 percent of Grazax patients had side effects believed to be caused by the treatment — the most common being itching and swelling in the mouth, ear itchiness and throat irritation.

A clinical trial aimed at winning approval for Grazax in the U.S. is currently underway.