New evidence supports the hypothesis that postorgasmic illness syndrome (POIS) in men involves a hyper-reactive immune response of the mucosal epithelium that lines the urinary tract to seminal fluid.

The term 'POIS' was coined 9 years ago by the Netherlands-based duo Marcel Waldinger and Dave Schweitzer. At that time, they described two patients who developed debilitating flu-like symptoms soon after ejaculation. The severe fatigue, fever, nasal congestion, irritability and poor concentration resolved spontaneously within a week.

After Waldinger and Schweitzer published their description of the first two patients in 2002, men afflicted by the same phenomenon began to present to their clinic in increasing numbers. Now, two papers in The Journal of Sexual Medicine summarize the findings from study of a 45-strong cohort of Dutch Caucasian POIS patients.

All participants satisfied the 5 criteria proposed by the researchers for establishment of a POIS diagnosis. The criteria are: at least one of 10 symptoms (see above for examples); onset of symptoms within a few hours of spontaneous ejaculation (that is, during sleep) or ejaculation triggered by masturbation or intercourse; symptoms develop in response to more than 90% of ejaculations; most symptoms persist for about 2–7 days; symptoms resolve spontaneously thereafter.

The researchers' hunch that allergy to one's own semen underlies POIS was borne out by skin-prick testing of 33 patients. Autologous semen diluted 1 in 40,000 with saline was injected intracutaneously on the volar side of the forearm. Almost 90% of study participants had a positive reaction to this procedure. Saline-only skin-prick tests elicited negligible reactions.

Two of the men who returned a positive skin-prick test elected to undergo hyposensitization therapy. These patients had been severely affected by POIS for many years. Aged in their fifties at the time of treatment, they had experienced their first POIS episode around the age of 20 years. Both abstained from sexual activity as much as possible in order to prevent symptom onset.

Inoculation every 2 weeks with increasing concentrations of autologous semen resulted in dramatic amelioration of symptoms for both men. The severity of postejaculatory impairment decreased gradually over the treatment period. The first patient rated the magnitude of improvement at 60% after 31 months, and the second at 90% after 15 months.

Interestingly, premature ejaculation was a key feature of the history of one of these men, and had the same date of onset as POIS (age 19 years). His self-perceived intravaginal ejaculation latency time increased remarkably during the course of hyposensitization therapy—from 10 s to 5–10 min. Premature ejaculation was reported by just over half of the men in the larger 45-strong study population.

“The coincidence of POIS and lifelong premature ejaculation is remarkable and deserves further attention in future POIS treatment strategies” state the investigators. They also recommend including POIS in published lists of reactive postejaculatory syndromes in order to raise awareness among clinicians.