onset of action

Onset of action is the duration of time it takes for a drug's effects to come to prominence upon administration. With oral administration, it typically ranges anywhere from 20 minutes to over an hour, depending on the drug in question. Other methods of ingestion such as smoking or injection can take as little as seconds to minutes to take effect. The determination of the onset of action, however, is not completely dependent upon route of administration. There are several other factors that determine the onset of action for a specific drug, including drug formulation, dosage, and the patient receiving the drug.