A Swiss team at Basle University taught 66 people with hay-fever the art of hypnosis and found it helped them alleviate symptoms such as runny nose.
The volunteers also took their regular anti-hay-fever drugs, but the effect of hypnosis appeared to be additive and reduce the doses they needed to take.
The findings appear in the medical journal Psychotherapy and Psychosomatics.
The study took place over two years and included two hay fever seasons.
During the first year, some of the volunteers with hay-fever were taught and asked to regularly practise hypnosis as well as take their usual allergy medicine.
The hypnosis training consisted of one two-hour session with an experienced trainer.
The remaining volunteers had no other treatment apart from their normal allergy medication.
After a year, the researchers found the volunteers who had been using self-hypnosis had reported fewer symptoms related to hay-fever than their fellow volunteers.