Nimesulide is a non-steroidal anti-inflammatory drug (NSAID). It works by blocking the release of certain chemical messengers that cause pain and inflammation (redness and swelling). Paracetamol is an analgesic (pain reliever) and antipyretic (fever reducer). It blocks the release of certain chemical messengers in the brain that are responsible for pain and fever. Phenylephrine is a nasal decongestant which narrows the small blood vessels providing relief from congestion or stuffiness in the nose. Caffeine is a central nervous system stimulant which works by blocking the action of certain natural substances (adenosine and phosphodiesterase). It can increase alertness and improve energy levels.