The time it takes for a medicine to work varies from medicine to medicine. For example, glyceryl trinitrate, a medicine commonly used to treat chest pain associated with angina, is used as a tablet and, increasingly in the form of a spray, and provides almost immediate relief from the symptoms. In contrast, some medicines used to treat anxiety, nervous disorders and depression can have a delayed effect and, depending on the drug, days or even several weeks’ treatment may be required before a patient experiences real benefit.
How quickly do medicines reach their site of action in the body?
For more information on the various methods of taking medicines, please read 'How to take medicine '