Some side-effects appear soon after treatment with a drug is started as the body adjusts to treatment with the new drug. Such side-effects often lessen, become manageable or go away completely after a few days, weeks or months. They are often called short-term side-effects.

Other side-effects may only appear after a number of months or even years of treatment with a drug, and these are called long-term side-effects.

Drugs sometimes cause side-effects that were not identified during the research into their development and only become clear when the drug is being taken by lots of people for a very long period. It makes good sense to tell your doctor about any unusual symptoms you develop so the cause can be investigated and you can take the most appropriate action.