A white crystalline compound, acetyl salicylic acid (CH3.CO.O.C6H4.CO.OH) widely used as a drug for relief of pain and alleviation of fever. It has analgesic, antipyretic, and antiinflammatory properties, and is one of a class of agents called non-steroidal antiinflammatory drugs (NSAIDs). The name was originally a trade name, but has become the preferred name for the substance. It is actually a prodrug, liberating salicylic acid, the ultimate pharmacologically active agent, in the intestines. It is more effective when taken orally than is salicylic acid, because it dissolves more readily.