Dutch researchers have reported the existence of post-orgasmic illness syndrome or POIS that affect some men.

The symptoms of the syndrome that manifest themselves after an ejaculation are feverishness, runny nose, extreme fatigue and burning eyes, which can go on for a week.
Waldinger treated two of the men with the hyposensitization therapy which meant being repeatedly exposed to small but gradually increasing amounts of the allergen over several years to build up resistance.
Although the syndrome had been known to exist earlier, it was not common knowledge, mostly because of reluctance to seek medical help. Waldinger also states that the findings "contradict the idea that the complaints have a psychological cause."
Patients experiencing the symptoms of POIS should consult a physician who specializes in sexual dysfunction and to seek the counseling of a mental health professional to discuss the implications of living with POIS.
Source-Medindia