Although rare, women can be affected by an allergy to semen, but I have never seen a case. In 2006, an allergy specialist in New York reported on semen allergy. Symptoms included local itching, burning and swelling after intercourse. Some women have experienced more severe reactions such as breathing problems, hives and generalized swelling. Some required hospitalization. Another possibility is that you could be reacting to other allergens transmitted through seminal fluid – such as antibiotics or other medications that your boyfriend might be taking or foods and beverages that he consumes.
In a survey of 1,073 women who sought information about reactions to their partners, 13 percent were found to have allergies to proteins common in semen. This reaction is known as human seminal plasma protein hypersensitivity (SPH). Allergic women produce an antibody to the proteins. In most cases women are allergic only to one man's semen but some have reported reactions to several men. You're more likely to be prone to semen allergy if you have other allergies.
Two types of conventional treatment are available. The first is desensitization, which exposes patients to diluted doses of the allergen. The second involves removing proteins known to interfere with desensitization from semen plasma and then injecting small amounts of the processed semen at regular intervals.
You might consult an allergist to determine whether you really do have a semen allergy and if treatment would be worthwhile. Or you could ask your boyfriend to use a condom to see if limiting your exposure to his semen prevents your reactions. I would also recommend trying a mind/body approach such as hypnosis.
Andrew Weil, M.D.