Aspirin is a salicylate drug, often used as an analgesic to relieve minor aches and pains. Major Charles Kawalsky was taking aspirin to try to cure numerous headaches he was getting but they weren't working because his headaches were being caused by an immature symbiote. (SG1: "The Enemy Within")
On the planet Eden, Lt. Tamara Johansen found several plants that had analgesic properties similar to aspirin and gave some to Camile Wray. (SGU: "Faith")