Today we’d like to do our best to answer a question we get asked a lot – how long does Cannabis stay in your system?

There are a couple of factors at play here – how often you smoke and how fast your metabolic system works – your metabolism rate.

In the UK regular drug testing outside some special professions is rare which is a very good thing – in the US most employees are subjected to drug tests, where positive results could lead to job loss, so it is understandable that people want to be cautious when current and future employers will often ask you to undergo a urine test.:

The most common drug test is a urine test. So how long will cannabis show up in your urine after you stop smoking?

Short answer: It depends.

Urine tests are designed to detect a chemical called THC-COOH which is produced when your liver breaks down THC – this stays in your system a lot longer than THC itself.

In the USA, most drug screening companies have a cutoff level of 50 ng/mL although it’s been heard to be as low as 20 ng/mL.

The THC metabolism rate varies from person to person, and of course how much you ingested is also a big factor.

From studies done we can see that new or unseasoned / occasional smokers will probably test positive for Cannabis for between 1-3 days after consumption.

If you are not a regular cannabis user, you should be below 50 ng/mL after 4 days (96 Hours).

However if you use cannabis regularly, you can expect it to stay in your system for a lot longer – around a week or so – after ten days frequent cannabis users should pass the 50 ng/mL threshold, but this is not a guarantee!

Other studies have shown that cannabinoids can stay in your system for even longer – up to 30 days after use for heavy users. One extreme reported case had somebody that smoked heavily for 10 year who tested above 20 ng/ml after 67 days without using cannabis!

As mentioned numerous times above, no definitive answer can be given, but broadly speaking THC stays in your system for between 1-10 days depending on how often you consume cannabis.

Cannabis Limits for Drug Driving Tests in the UK

The Cannabis Geek has this to say on the subject:

For those interested in how long cannabis stays in your blood, for the purposes of DUI tests, check out this graphic. As you can see, after roughly two hours, most of the THC has gone, and certainly takes you below the legal levels of 2ng in the UK, or 5ng in Washington state.

People tend to mistake THC presence for that of carboxy-THC, which THC gets converted to by the body (metabolite). The latter can stay in the system for weeks, but the former is something which is only present for a matter of hours, before the body converts it into carboxy-THC. Modern science can and does easily distinguish between the two.

The reality is that after just a couple of hours, somebody who has consumed cannabis would most likely have less than the legal limit of ‘THC’ in their system.

This is good news and clears up some of the confusion UK drivers are currently facing after police introduced drug driving tests back in 2014.