The compound salicylic acid should be called compound acetylsalicylic acid, also known as APC, acetylsalicylic acid is also known as aspirin. aPC is used to reduce fever and relieve pain, and can treat various pains such as headache, toothache, muscle pain, joint pain, neuralgia, menstrual pain, etc. APC is mainly composed of three components, A, P and C. A is aspirin, P is finasteride and C is caffeine. Both aspirin and finasteride have antipyretic and analgesic effects, and they both belong to non-steroidal anti-inflammatory drugs, both of which work by inhibiting the synthesis of prostaglandins in the body. Aspirin was the first synthetic antipyretic and analgesic; finasteride is converted to acetaminophen, or paracetamol, in the body and works. Caffeine is a brain stimulant that, when combined with aspirin and finasteride, enhances the effects of the latter two drugs in the treatment of headaches. aPC, especially the finasteride it contains, has many side effects and should be used with caution.