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Cannabis and Your Health

Date of publication: Nov 2002

Introduction

Any drug can cause harm given the wrong set of circumstances and cannabis is no exception.

The same goes for legal drugs like alcohol and tobacco.

While cannabis is illegal, some people still choose to use it. If you choose to use cannabis you should know the full facts about how it might affect you.

There are also some situations where the chance of harm from using cannabis may be greater - like when you are:
  • feeling depressed or stressed
  • trying to focus on study or school work
  • driving a motor vehicle or operating dangerous machinery, especially when mixing cannabis and alcohol.
There are also times when using cannabis can put you at a disadvantage in relation to others, like using it before you play sport, doing things requiring co-ordination, or when it’s important that you concentrate.

This information will help you make a more informed decision about using cannabis and may help reduce any harm cannabis could cause you.

What is cannabis?

Cannabis is a drug prepared from the plant cannabis sativa. The three common forms of cannabis are:

Marijuana - made from the small stalks, dried leaves and flowering tops (‘buds’). It is usually smoked in a hand rolled cigarette or ‘joint’, and can be eaten in cakes or biscuits.

Hashish - dried resin and compressed flowers that usually comes as a block.

Hash oil - sticky concentrated liquid made from leaves and buds.

How does cannabis work?

The chemical in cannabis that causes you to get ‘high’ or ‘stoned’ is called THC (delta-9-tetrahydrocannabinol). When cannabis is smoked or eaten THC enters the bloodstream and goes to the brain.

When in the brain THC binds to tiny parts of the brain called brain receptors.

If enough THC binds with these brain receptors your behaviour will be affected and you become ‘stoned’.

What are the possible effects of using cannabis?

The effects of using cannabis can be put into two separate groups:
  • immediate/short-term effects
  • long-term effects.
Immediate/short-term effects

These are the likely short-term effects of a single dose (eg, after smoking one or more joints in a session). These effects can happen soon after the drug is in your system or while you are ‘stoned’ and can last up to 3-4 hours.

They may include:
  • feelings of happiness and relaxation
  • talkativeness and laughter
  • changes in mood, perceptions, thoughts or feelings
  • feelings of hunger – ‘the munchies’
  • time seeming to speed up or slow down
  • some experiences seeming to be intensified – eg, watching films or listening to music
  • paranoia, anxiety, or panic – especially in inexperienced users or those who take a large dose
  • impaired concentration, short-term memory, and information processing that affects learning at school or work performance
  • impaired reaction time and co-ordination that leads to a higher risk of accidents, eg, while driving, especially if you have also been drinking
  • worsening symptoms of mental problems in those with a history of such problems
  • increased heart rate and changes in blood pressure.
Whether you experience these effects as positive or negative or a mix of both will depend on various factors. These include your previous experience with cannabis, the amount you use, your mood at the time, or the environment you use the drug in.

Long-term effects

These are the possible long-term effects of regular cannabis use (eg, after smoking daily or regularly for a period of years).

These effects may include:
  • breathing system problems - eg, bronchitis, emphysema, wheeziness, shortness of breath
  • becoming dependent on cannabis, so that you are unable to stop using cannabis or control your use. Risk of dependency appears greater if you start using cannabis at an early age
  • subtle impairments to your thinking processes - such as organising complex information and using your attention and memory processes. It’s unclear if such effects are reversible. Evidence suggests that long-term use does not cause severe damage to thinking processes, or cause permanent brain damage
  • increased risk of cancers of the lung, mouth, throat, and the canal from mouth to stomach
  • impaired educational achievement in adolescents, and underachievement in adults’ work performance if their work requires high-level thinking skills
  • a risk of worsening symptoms for those with physical problems (such as breathing-system problems) or mental problems (such as schizophrenia)
  • if you smoke while pregnant your baby could be affected (eg, born with a low birth-weight)
  • a possible increased risk for some young people using cannabis regularly (ie, once a week or more) to progress to other drugs.
Additionally, if you use cannabis regularly, it may lead to problems relating to family and friends which upset everybody.

The evidence for some of these effects is complex and cannot all be summarised in a pamphlet. For more detail, check out the web-sites listed further down this page.

Will cannabis always produce the same effects?

No. The effects of cannabis can be different each time someone uses it and can also be different for different people. The effects of cannabis depend on:

The Drug

How much cannabis is used and its strength will affect its impact. Generally marijuana is weaker than hash and hash is weaker than hash oil. Using other drugs with cannabis, such as alcohol, creates different effects, and does not cancel out the effect of either cannabis or alcohol or any other drug.

The Person

The user’s mental state (eg, mood) and physical characteristics, along with past experience with cannabis will also affect reactions to the drug.

The Setting

The environment in which cannabis is used can also play a part. If you are with people you know and in a familiar place you may experience fewer feelings of anxiety or panic than you would if you were in a strange environment, or something unexpected happened.

The occasional use of cannabis may not cause the average person significant harm. However, the risks of short-term harm will increase if cannabis is used in situations when it’s important to concentrate or be totally physically co-ordinated (eg, driving). Risks also increase if your unique physical or mental characteristics mean that you react negatively to the drug.

The risks of long-term harm will increase if you use cannabis regularly or heavily over a long period of time (eg, daily over a number or years).

Where do I go for more information about cannabis and other drugs?

The scientific evidence about the health effects of cannabis is complex and there are some gaps in our knowledge.

For general drug policy information check out the information contained in the Cannabis section of this website.

Information about cannabis is available for young people on the Urge/Whakamanawa youth website: www.urge.org.nz or www.whakamanawa.co.nz

Or you can visit ‘Sorted’ on www.waitematahealth.co.nz

Where do I go for help?

If you or someone you know needs help for a problem with cannabis, contact one of the following services:

Alcohol Drug Helpline
0800 787 797 (10am - 10pm seven days a week)

Narcotics Anonymous
Wellington: 04 801 9933
Auckland: 09 303 1449
Christchurch: 03 365 0686

Alcohol and Drug Treatment Services
phone your nearest hospital

Youthline
0800 376 633

Citizens Advice Bureau
0800 367 222

Your doctor or a local GP
look under Registered Medical Practitioners at the front of your phone book.

Emergency
dial 111 for an ambulance



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