Pharmacology & biology

Half-life

Also known as: t1/2 · elimination half-life

The time it takes for the concentration of a drug in the body to fall by half.

In plain terms

Half-life sets the dosing interval and how long it takes to reach steady state — roughly four to five half-lives. It also sets how long a problem lasts: a drug with a one-week half-life is still substantially present a fortnight after the last dose.

This is why "just stop taking it" is not immediate advice for a long-acting agent, and why side effects from weekly GLP-1 drugs can persist well past the decision to discontinue.

Compounds where this comes up

Guides that use this term

What happens when you stop a GLP-1

One year after semaglutide was withdrawn, participants had regained two-thirds of the weight they lost, and their cardiometabolic gains reverted. The withdrawal trials, read honestly.

Educational reference only. Pepperz does not provide medical advice, diagnosis, treatment, prescribing guidance, or dosing recommendations.