Damason-P is a combination medication that contains aspirin (acetylsalicylic acid), caffeine, and a barbiturate called phenobarbital. Aspirin is a nonsteroidal anti-inflammatory drug (NSAID) that helps relieve pain, reduce inflammation, and lower fever. Caffeine is a central nervous system stimulant that can enhance the pain-relieving effects of aspirin. Phenobarbital is a barbiturate that has sedative properties and can help with relaxation and sleep.