This condition is called post orgasmic illness syndrome (POIS). People with POIS often experience flu-like or allergic-like reactions after ejaculating. POIS was first defined in 2002, but there’s still a lot that we don’t know about the condition. While it’s rare, it can be debilitating. Consult a doctor if you think you may be allergic to your own semen.

Source: www.ncbi.nlm.nih.gov(opens in a new tab)