The Neurocritic: Snotty or Nice?

Bhutta MF, Maxwell H. Sneezing induced by sexual ideation or orgasm: an under-reported phenomenon. J R Soc Med. 2008 Dec;101(12):587-91.

We describe a hitherto under-recognized curious response in some individuals: of sneezing in response either to sexual ideation or in response to orgasm. Our review suggests that it may be much more common than expected. We surmise that an indiscrete stimulation of the parasympathetic nervous system may be an underlying mechanism to explain this and other reported unusual triggers of sneezing.

First, we had the ACHOO (autosomal dominant compelling helio-ophthalmic outburst) syndrome, commonly known as photic sneezing:

The probable cause is a congenital malfunction in nerve signals in the trigeminal nerve nuclei. The fifth cranial nerve, called the trigeminal nerve, is apparently responsible for sneezes. Research suggests that some people have an association between this nerve and the nerve that transmits visual impulses to the brain. Overstimulation of the optic nerve triggers the trigeminal nerve, and this causes the photic sneeze reflex.

Now we have sneezing in response to orgasm or even thinking about sex. Here's a poor bloke writing in to The Times Online:

I’m a middle-aged man, and when I climax I have sneezing fits, which spoil the mood. Can I prevent this?
SUZI GODSON answers:

Impotence? Premature ejaculation? Inorgasmia? Sneezing? In the greater scheme of things, keeping a box of tissues by the bed is, I would suggest, a manageable sexual burden. After all, sneezing is not an entirely unpleasant experience. Indeed, it is often compared to orgasm because it is messy, takes about a second, requires copious Kleenex and strangers bless you afterwards.

If it makes you feel better, you are suffering from a serious-sounding but harmless medical condition. The propensity to sneeze at orgasm is closely related to the Achoo syndrome, commonly known as photic sneezing.

This is a genetically inherited neurological phenomenon, which occurs when exposure to bright light triggers pupil constriction in the eye. Pupil constriction is a function that is controlled by the brain stem, the multi-tasking lower part of the brain. The brain stem connects the spinal cord to the brain and plays a vital role in a smorgasbord of neurological functions that include breathing, digestion, heart rate, blood pressure and arousal. Because the neural pathways for these functions run very close to each other, it is thought that light-sensitive sneezing, sneezing after a meal or post-coital sneezing occur when the pathways get muddled up with the pathway that registers irritation in the nose.