In some cases, the bites of venomous snakes called Russell's vipers, which inhabit South and Southeast Asian countries, can cause bleeding in the pituitary gland. This damages the organ and can prevent it from performing its basic function, the production of hormones including those that regulate sexual functioning.

In a report published in October 1987 in the journal The Lancet, researchers examined 33 cases of patients bitten by Russell's vipers. Some of those patients developed serious hormonal abnormalities, which resulted in decreased libido; loss of pubic and armpit hair; erection problems in men; and irregular, scant or absent menstrual periods in women.