How Long Does Cannabis Stay in your System?

Cannabis is an addictive drug, usually smoked in order to achieve a ‘high’ which makes an individual feel a variety of both positive and negative effects.

The effects of cannabis can vary, but the substance usually distorts an individual’s perception of the world, either making them especially calm or anxious.

How long cannabis remains present in the body depends on various factors. It can last for different periods of time in different parts of the body, ranging from just a few days to several months.

Those who are conscious about the presence of cannabis within their system tend to also be concerned about their relationship with the substance. If there is concern about a potential addiction to cannabis, speaking to a GP is the recommended thing to do.

Cannabis and the body

Cannabis, otherwise referred to as ‘weed’, is a psychoactive drug, commonly smoked to achieve a pleasurable ‘high’. It is currently illegal in the UK, and is deemed to have a high abuse risk.

While the effects of cannabis can vary from person to person, those who smoke it commonly feel more relaxed, drowsy, or talkative. It can also cause negative effects such as enhanced paranoia, hallucinations, and disorientation.

Due to these effects, it is common for users to be concerned about how long cannabis remains within the body. Its presence might pose risks if an individual gets behind the wheel of a car or has a dangerous job.

How long does it remain in the body?

When an individual uses cannabis, the body breaks down its core components. The main chemical substance to note here is THC (Delta-9-Tetrahydrocannabinol).

After entering the bloodstream, THC eventually makes its way to the liver where it is broken down into metabolites. There are around 80 of these substances in cannabis, and it is these that drug tests detect when checking for the drug’s presence.

Metabolites remain within an individual’s system for a while after the effects of cannabis have worn off, and they can be traced in several areas of the body for different durations of time.

1. Urine

The most common testing method for cannabis is via the urine. This is because it tends to hold a higher concentration of metabolites for a longer detection time [1].

Due to metabolites tending to attach themselves to fat molecules within the body, it can take a while for them to pass through the system.

How many times a week an individual tends to use cannabis can greatly affect how long metabolites can be detectable within the urine:

  • 3 times a week – 3 days
  • 4 times a week – 5-7 days
  • Daily – 10-15 days
  • Several times a day – 30+ days

2. Blood

After using cannabis, it can be detected within the bloodstream almost immediately. That which is not broken down into metabolites is redistributed by the kidney, meaning that it can remain present for a while.

Cannabis metabolites tend to remain within the blood for around 1-2 days following use. However, for those who use it frequently, it can last for up to 25 days.

3. Saliva

The most common way of ingesting cannabis is through smoking it. This means that the substance is very commonly detectable in the saliva, often through its exposure to the resulting smoke.

For an individual who occasionally uses cannabis, the substance can remain in the saliva for 1-3 days. For more frequent users, it can remain for up to a month.

4. Hair

As cannabis metabolites circle the body through the bloodstream, very small blood vessels carry them into an individual’s hair follicles.

Hair tends to hold these metabolites for a while, and cannabis can still be traceable for up to 3 months after use.

What factors can affect this duration?

As suggested above, there are several factors that can influence how long cannabis remains within the body’s system.

1. Size of dose

Higher quantities of cannabis tend to last much longer in the body than small ones.

As with many other bodily processes, it will take longer to break down the substance into metabolites if there is more of it.

Due to this, the body might take a while to break down and redistribute large doses of cannabis, meaning that new detectable metabolites can be produced several days after use.

2. Frequency of doses

Following the same principle as above, the more frequently an individual uses cannabis, the longer it will be detectable.

If the body is constantly having to break down new cannabis, the presence of metabolites will constantly be renewed.

Also, after sustained use, the body will gradually become less efficient at breaking cannabis down. The process may slow, meaning the original substance may last longer within the bloodstream.

How cannabis is ingested

The method of use is known to greatly influence the effects of many recreational drugs, and this applies to cannabis too. How it is taken can affect how long it remains in the body.

It is common for individuals to smoke cannabis, but it can also be ingested. This tends to increase the amount of time it remains in the body compared to the former, more popular method.

1. How pure the cannabis is

Due to it being illegal in the UK, those who frequently use cannabis are forced to acquire it via illicit means. As a result, the strength of it can vary from person to person.

Cannabis can come in different types, and each will have different effects on the individual taking it. Those with a stronger THC level will last for much longer in the body, for example, than weaker ones.

2. The individual themselves

How the body processes cannabis is also influenced by its own state and condition. The characteristics of the individual taking the substance can affect how it is broken into metabolites.

For example, those who are younger, have faster metabolisms, and have healthier body mass indexes (BMI) are able to break the cannabis down much faster, and so the presence of the resulting metabolites is much more short-lived.

On average, men are also able to break down cannabis much faster than women.

Cannabis that is not broken down can be stored within fat, meaning it might be traceable within the body for a longer period of time if the body does not metabolise it quickly.

Cannabis and addiction

Individuals concerned about the amount of time that cannabis remains within their system tend to also be concerned about addiction.

The substance is highly addictive, and those who use it frequently are at risk of developing an unhealthy dependence on it. Some of the signs of this include:

  • Absences from school or work due to cannabis
  • Being dishonest or secretive about cannabis use
  • Continuing to use cannabis after health risks
  • Being unable to stop cannabis use

Those who are concerned about their cannabis use, or that of a friend or loved one, are recommended to contact their GP to discuss the nature of addiction and what treatment options are available.