NHS website - How long does cannabis stay in the body after smoking?

How long does cannabis stay in the body after smoking?

It depends on how often and how much cannabis a person smokes and the potency (strength) of the cannabis. 

In general, the less cannabis that’s smoked, and the less often it’s smoked, the quicker it leaves the body.

THC, the active chemical in cannabis, is stored in the fat cells and therefore takes longer to fully clear the body than any other common drug. The stronger the strain of cannabis, the more THC it contains.

Drug testing equipment, as used by the police, works by measuring the amount of THC in a urine sample.

A review of data compiled by the US National Drug Court Institute estimated that:

• an occasional or first-time user would probably test positive up to four days after last using
• a frequent user would probably test positive up to 10 days after last using
• a very heavy user could test positive up to one to two months after last using

Long-term use of cannabis can make you depressed and make you less motivated.

Further information:

• Does cannabis interact with antidepressants or lithium?
• Drugs and drug abuse