What are the effects of cannabis use?

Marie Law Alphabiolabs

By Marie Law, Head of Toxicology at AlphaBiolabs
Last reviewed: 07/03/2023

Cannabis is the most-used illicit drug in England and Wales, and is known to cause a range of side effects.

In this article, we take a closer look at cannabis, what it does to the body, the short-term and long-term effects of cannabis use, and how long cannabis stays in your system.

Table of contents
  • What is cannabis?
  • What does it do to your body when you take cannabis?
  • Is cannabis addictive?
  • What are the physical effects of cannabis use?
  • How can cannabis impact your mental health?
  • What are the long-term effects of cannabis use?
  • Can cannabis be used for medical purposes?
  • How long does cannabis/THC stay in your body?
  • What is the difference between THC and CBD?
  • Where can I buy a drug test?

What is cannabis?

Commonly referred to as marijuana, weed, dope or hash, cannabis is a plant-based drug derived from the Cannabis sativa or Cannabis indica plant.

Popular among recreational drug users, it is often sold as a soft lump of dried green or brown herbs. However, it comes in many different forms including skunk, which is a particularly strong strain of the substance that is bright green and covered in crystals.

Cannabis is most commonly smoked or vaped, but some people also add it to food and drink products known as ‘edibles’ or ‘cannabis edibles’.

Other forms of cannabis include cannabidiol (CBD), a cannabinoid commonly sold online and in select shops in the form of CBD oil, and cannabinol (CBN), a compound found in the cannabis plant that produces few, if any, psychoactive effects.

Under UK law, cannabis is classified as a Class B drug alongside ketamine and amphetamines. Possession of Class B drugs, including cannabis, could result in up to five years in prison and/or an unlimited fine.

Anyone found to be in possession of cannabis with intent to supply or cultivating cannabis with the intention of distributing could receive up to 14 years in prison and/or an unlimited fine.

What does it do to your body when you take cannabis?

It is important to remember that drugs affect people in different ways. Not everyone will have the same experience with the same substances, and drugs can even affect the same person differently when taken at a different time.

Cannabis is a psychoactive drug. The effect it has on the person taking it can depend on a variety of factors including the kind of person they are usually, their mood when taking it, how much cannabis they have taken, frequency of use, and how much tetrahydrocannabinol (THC) the drug contains.

THC is the main psychoactive compound found in cannabis. When a person uses cannabis, THC is released into the system. This alters normal brain communication and affects emotions, thinking, memory, concentration, and movement.

Some people might feel relaxed and giggly after using cannabis while others can become anxious and paranoid.

Other side effects of cannabis include increased hunger and drowsiness. In some instances, sickness and nausea can occur, as can mild hallucinations.

Long-term use has also been linked to mental health problems such as depression and anxiety.

Is cannabis addictive?

Yes, cannabis is addictive. People who use cannabis regularly may experience cravings and withdrawal symptoms when they stop using it, leading to the development of harmful addictions.

When an individual ingests cannabis, either through smoking, vaping, or eating it, this alters the way the brain works and causes it to release dopamine.

Dopamine, the brain’s ‘feel-good’ chemical creates feelings of euphoria, pleasure, and reward. These powerful sensations cause some people to become addicted and dependent on cannabis.

People who use cannabis on a regular basis are also more likely to build up a tolerance to it. This means that they will require even more of the drug over time to experience the same ‘high’.

What are the physical effects of cannabis use?

Although the effects of cannabis can wear off in as little as an hour, depending on how much of the substance was consumed, using cannabis regularly has been linked to several physical health problems including:

  • Breathing issues
  • Increased heart rate and blood pressure
  • Coughing
  • Fertility concerns
  • Insomnia/difficulty sleeping

Short-term physical effects of cannabis can include increased hunger, nausea, vomiting and drowsiness.

How can cannabis impact your mental health?

As well as the potential for developing physical health problems, people who use cannabis on a regular basis also put themselves at increased risk of developing psychological and mental health problems.

Heavy cannabis use has been linked to:

  • Hallucinations
  • Paranoia
  • Memory problems
  • Psychotic disorders, including schizophrenia
  • Depression
  • Anxiety

A study published by the Addiction and Mental Health Group at the University of Bath also linked stronger strains of cannabis to addiction and mental health problems.

What are the long-term effects of cannabis use?

The effects of cannabis can wear off in as little as an hour, depending on how much cannabis was consumed.

However, cannabis use over a prolonged period has been shown to cause several long-term effects and increase the risk of serious health problems, including:

  • Heart and blood pressure issues
  • Breathing difficulties
  • Fertility concerns
  • Mood swings
  • Difficulty sleeping
  • Poor mental health episodes

Can cannabis be used for medical purposes?

Although rare, cannabis-based medicines may be prescribed in the UK to relieve symptoms of certain conditions.

Circumstances in which a person might be prescribed medical cannabis include children and adults with severe or rare forms of epilepsy, adults undergoing chemotherapy, and people with multiple sclerosis (MS) dealing with muscle spasms and stiffness.

However, medical cannabis would only be considered where other treatments had not helped or had been deemed unsuitable.

How long does cannabis/THC stay in your body?

When a person consumes cannabis a proportion of the drug and its metabolites are released into the body and bloodstream.

A small amount of the drug is then excreted from the body in a variety of ways.

How long cannabis and THC remains in the system and how quickly someone might feel the effects depends on how the drug was consumed, frequency of usage, how much cannabis was taken, how much THC is in it and the weight and metabolism of the individual.

When smoked, cannabis and its effects can be felt in as little as one minute. When eaten, the effects can be felt up to 45 minutes later and can last for several hours.

It can take days for someone to feel normal again after consuming cannabis.

Long after the drug was first consumed and the ‘high’ has worn off, cannabis use remains detectable by a drug test.

Drug testing methods that can be used to detect cannabis use include oral fluid (saliva) drug testing, urine drug testing, hair drug testing and nail drug testing.

What is the difference between THC and CBD?

Although both cannabidiol (CBD) and tetrahydrocannabinol (THC) come from the Cannabis sativa plant and are classed as cannabinoids, there are some key differences between them.

THC is the main psychoactive ingredient in cannabis and causes the ‘high’ that people feel when taking the substance. In the UK, it is illegal for THC to be used for non-medical purposes or recreationally.

CBD produces little if any psychoactive effects and CBD products are legal – albeit, subject to heavy regulation.

CBD products must contain less than 0.2% (trace levels) of THC to be legally bought and sold in the UK.

When used in medical settings, both THC and CBD can be prescribed to treat certain conditions including epilepsy, multiple sclerosis (MS), and nausea and vomiting in adults undergoing chemotherapy, where other treatments have previously failed or been unsuitable.

Where can I buy a drug test?

AlphaBiolabs offers two types of home drug tests, designed to give you peace of mind or enable you to seek support for a friend or loved one who is struggling with substance misuse, including cannabis misuse.

  • Home Urine Drug Test Kit (£18) – this easy-to-use home drug testing kit can detect drugs and their metabolites in a urine sample. The self-contained screening kit includes built-in test strips, allowing you to read the results in just 5 minutes
  • Drug and Alcohol Nail Test (from £99) – this test can detect drug use for a period of up to 12 months prior to samples being collected, with only a sample of fingernail clippings or toenail clippings required. Simply follow the instructions included in your test kit to collect your nail clipping samples and return them to our accredited laboratory for testing

Please be aware that our home drug test kits are for peace of mind only, and the results cannot be used in court. If you require a drug test for official matters, you will need a legally-instructed drug test.

For confidential advice about which test might best suit your needs, you can also call our Customer Services team on 0333 600 1300 or email info@alphabiolabs.com.

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Marie Law

Marie Law

Head of Toxicology at AlphaBiolabs

A highly-skilled and respected scientist with over 13 years’ experience in the field of forensics, Marie joined AlphaBiolabs in 2022 and oversees the company’s growing toxicology team.

As Head of Toxicology, Marie’s day-to-day responsibilities include maintaining the highest quality testing standards for toxicology and further enhancing AlphaBiolabs’ drug and alcohol testing services for members of the public, the legal sector, and the workplace sector.

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