Percocet 7.5-325 mg is designed for short-term relief of moderate to severe pain, especially after an injury or surgery. This white oval pill contains Oxycodone and acetaminophen. Oxycodone works by affecting the brain and central nervous system to help reduce pain, and it can also be effective for cough relief. Meanwhile, acetaminophen helps lower fever. You can expect it to start working within about 4 to 6 hours.