Pathophysiology
Most recently, in early 2011, Professor Waldinger and collaborators further characterized POIS, proposed a specific immunological mechanism, and empirically supported their hypothesis on 45 Dutch Caucasian males. This study concluded that both Type-1 and Type-4 allergy to male's own semen contribute to symptoms of the illness.
Dexter speculates that POIS could be caused by a lack of progesterone, a powerful neurosteroid, or a defect in neurosteroid precursor synthesis. In the latter case, the same treatment may not be effective for different sufferers. Different sufferers may have different missing precursors, ultimately leading to a deficiency of the same particular neurosteroid, causing similar symptoms.
An array of more subtle, lingering symptoms after orgasm, which would not constitute POIS, may contribute to habituation between mates. They may show up as restlessness, irritability, increased sexual frustration, apathy, sluggishness, neediness, dissatisfaction with a mate, or weepiness over the days or weeks after intense sexual stimulation. Such phenomena may be part of human mating physiology itself. Habituation to a mate can drive the search for novel mates (the Coolidge effect). Possible neurochemical mechanisms behind such effects are discussed in "The Passion Cycle."
One researcher suggests that the symptoms may be produced by an autoimmune reaction against any of various hormones or other substances secreted during and after sex. Another suggests that chemical imbalances in the brain may cause the symptoms.
It is difficult to demonstrate a causal relationship based on patient reports.
Read more about this topic: Postorgasmic Illness Syndrome