What is a half-life?

Half-life is a term used in pharmacology and nuclear chemistry to describe the time it takes for the concentration of a substance (such as a drug or radioactive isotope) to decrease by half in the body or a given environment. The half-life of a drug is an important parameter that influences its dosing frequency, duration of action, and potential for accumulation in the body.


In the context of drug metabolism and pharmacokinetics, the half-life of a drug determines how often it needs to be administered to maintain its therapeutic effects. For example, a drug with a short half-life may require multiple doses per day, while a drug with a longer half-life may only need to be taken once daily or even less frequently. 

Understanding the half-life of a drug is important for clinicians when prescribing medications, as well as for patients in understanding their medication regimen and the potential for drug interactions or side effects.

← Back to glossary home

Treatment that works is right at your fingertips.

Get started