Cannabis is a naturally occurring plant which comes in a variety of different forms including cannabis resin or hash, herbal cannabis and cannabis oil.

There are also other forms, such as edibles and tinctures, that are common in the medicinal cannabis market.

Risk factors

Cannabis can make some existing mental health symptoms worse and has been linked with the possible development of mental health issues.

The risk factors include an underlying vulnerability to mental health issues such as family history, heavy cannabis use from a young age over a long period of time or use of high potency cannabis.

Long-term use and dependency

People using cannabis every day over a prolonged period may develop a tolerance of the effects. They may need more to get the desired effects or may experience dependency.

Withdrawal effects can be reported where people become dependent.

The most commonly reported symptoms are:

  • difficulty sleeping
  • vivid dreams or nightmares
  • low mood
  • difficulty concentrating
  • irritability
  • cravings

Inhaling any substance into your lungs can cause irritation to the delicate tissue. This includes tobacco, cannabis and vaping products.

How to reduce harm

As cannabis may worsen anxiety and paranoia in some people, only use it where you feel safe and with people you trust. Avoid using cannabis if you’re prone to anxiety or have existing mental health problems.

Start low, go slow as potency can be hugely variable. Start with a very small dose and, if using more, increase dose cautiously. Give time for previous doses to wear off, about 30 minutes.

Using cannabis more safely

If you’re smoking, consider using a vapouriser so you can remove the tobacco. This will reduce the risk of lung damage.

Avoid holding smoke in your lungs or breathing in too deeply and take short puffs.

If smoking in pipes, use glass or steel, as they give off less unpleasant fumes than wood or plastic.

Water pipes (bongs) cause you to inhale more deeply which increases the risk of lung damage. Avoid sharing joints, vapes, pipes and bongs with others.

Eating cannabis will result in a much longer duration of effects, and more delayed onset of effects.

The effects will also be more hallucinogenic so dosage is very important. Start with a lower dose and avoid re-dosing for at least a couple of hours.


If you would like help or support related to drug use please visit support for people affected by drugs.

Further information

For further information on cannabis visit Crew.

Last updated:
01 December 2022