Why does MS make having sex painful?
Painful intercourse is termed dyspareunia and can occur from any number of reasons. In multiple sclerosis, the sensory circuits may be impacted which can lead to neuropathic pain anywhere in the body (that subserves those circuits). If the sensory nerves from the genitals (ie, perineum) to the brain are involved, the subsequent signal is altered and experienced as pain. Moreover, motor fibers, if involved, may also lead to spasms or painful contractions as well.
Other potential causes can include infection, anatomic changes including the bladder (particularly in women), and even mood alterations (ie, depression). Sometimes the reason is myriad and not just one of the possibilities listed above.
A potential place to start (after discussion with your neurologist) may be with a subspecialist in urology or gynecology (depending on gender) with interest/focus on treating sexual dysfunction.
Hope this helps.
A. Scott Nielsen MD MMSc
Neurologist and MS Specialist at Kaiser Permanente