The main disadvantage of aspirin is that…

Aspirin is most effective in relieving slight to moderately severe pain, particularly headache, muscle aches, and joint pains. It is less effective against deep-seated pain originating in internal organs. Because it suppresses inflammatory processes while relieving pain, it is still the treatment of choice for arthritis and related disorders. Aspirin is considered a relatively safe drug. Its chief drawback is its ability to irritate the lining of the stomach and cause bleeding. In large doses, however, aspirin is toxic, causing kidney damage and, in severe cases, death. Aspirin should never be given to children with viral diseases such as chicken pox or influenza. Such use has been associated with occurrences of the sometimes-fatal Reye's syndrome.