What does “Half-life” mean?

The time taken for the amount of a drug in the body to fall by half.

Half-life in plain English

The time taken for the amount of a drug in the body to fall by half.

Cannabinoids are fat-soluble and accumulate in body tissue with repeated use, which gives THC a long and variable terminal half-life — a major reason it remains detectable in urine testing for weeks after regular use.

A long half-life does not mean a long duration of effect. The effects wear off well before the substance has cleared.

Frequently asked questions

What does half-life mean?

The time taken for the amount of a drug in the body to fall by half.

Sources and further reading

Every factual statement on this page is drawn from the following public sources. Links open in a new tab and are not affiliated with Flora House.

  1. NICE guideline NG144: Cannabis-based medicinal products
  2. NHS: Medical cannabis (and cannabis oils)
  3. MHRA: The supply, manufacture, importation and distribution of unlicensed cannabis-based products for medicinal use

Patient guide · Written by the Flora House editorial team · Last reviewed: 8 September 2026