Dear Dr. Paul,
Why does my BF’s semen burn when it gets in my eyes?
In a word: Spermine. Spermine is a chemical that’s in semen. It is made by the prostate gland. It’s what gives semen its characteristic bleachy smell.
The material safety data sheet for commercially produced spermine says:
Danger! Corrosive. Causes eye and skin burns. May cause severe respiratory-tract irritation with possible burns. May cause severe digestive-tract irritation with possible burns. May cause central- nervous-system effects. May cause cardiac disturbances. Causes eye burns. May cause chemical conjunctivitis and corneal damage. Causes skin burns.
While the concentration of spermine in semen isn’t nearly as high as when you purchase the raw chemical, it’s high enough to make your eyes sting. Also, semen can be a bit alkaline, which could cause irritation. There may be other things in semen that cause eyeballs to burn, but the main culprit is most likely spermine.