How does aspirin relieve pain?
(Lansing State Journal, June 8, 1994)
There are two paths we can take to relieve this pain. One way is to act on the central nervous system - the brain and spinal cord. The other way is to act on the nerves that send the pain message to the central nervous system. Narcotics like morphine act on the central nervous system. Aspirin acts on the nerves.
Some chemical that stimulate the nerve endings to send the pain message are prostaglandins. Prostaglandins sensitize nerve endings, thus increasing the effect of other pain eliciting chemicals. Aspirin inhibits the release of prostaglandins and thus interferes with the message of pain.