Cannabis: the facts – Healthy body
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Cannabis (also known as marijuana, weed, pot, dope or grass) is the most widely used illegal drug in the UK.
The effects of cannabis vary from person to person:
- you may feel chilled out, relaxed and happy
- some people get the giggles or become more talkative
- hunger pangs (“the munchies”) are common
- colours may look more intense and music may sound better
- time may feel like it’s slowing down
Cannabis can have other effects too:
- if you’re not used to it, you may feel faint or sick
- it can make you sleepy and lethargic
- it can affect your memory
- it makes some people feel confused, anxious or paranoid, and some experience panic attacks and hallucinations – this is more common with stronger forms of cannabis like skunk or sinsemilla
- it interferes with your ability to drive safely
If you use cannabis regularly, it can make you demotivated and uninterested in other things going on in your life, such as education or work.
Long-term use can affect your ability to learn and concentrate.
Can you get addicted to cannabis?
Research shows that 10% of regular cannabis users become dependent on it. Your risk of getting addicted is higher if you start using it in your teens or use it every day.
As with other addictive drugs, such as cocaine and heroin, you can develop a tolerance to cannabis. This means you need more to get the same effect.
If you stop using it, you may get withdrawal symptoms, such as cravings, difficulty sleeping, mood swings, irritability and restlessness.
If you smoke cannabis with tobacco, you’re likely to get addicted to nicotine and risk getting tobacco-related diseases such as cancer and coronary heart disease.
If you cut down or give up, you will experience withdrawal from nicotine as well as cannabis.
Cannabis and mental health
Regular cannabis use increases your risk of developing a psychotic illness, such as schizophrenia. A psychotic illness is one where you have hallucinations (seeing things that are not really there) and delusions (believing things that are not really true).
Your risk of developing a psychotic illness is higher if:
- you start using cannabis at a young age
- you smoke stronger types, such as skunk
- you smoke it regularly
- you use it for a long time
- you smoke cannabis and also have other risk factors for schizophrenia, such as a family history of the illness
Cannabis also increases the risk of a relapse in people who already have schizophrenia, and it can make psychotic symptoms worse.
Other risks of cannabis
Cannabis can be harmful to your lungs
People who smoke cannabis regularly are more likely to have bronchitis (where the lining of your lungs gets irritated and inflamed).
Like tobacco smoke, cannabis smoke contains cancer-causing chemicals, but it’s not clear whether this raises your risk of cancer.
If you mix cannabis with tobacco to smoke it, you risk getting tobacco-related lung diseases, such as lung cancer and chronic obstructive pulmonary disease (COPD).
You’re more likely to be injured in a road traffic accident
If you drive while under the influence of cannabis, you’re more likely to be involved in an accident. This is one reason why drug driving, like drink driving, is illegal.
Cannabis may affect your fertility
Research in animals suggests that cannabis can interfere with sperm production in males and ovulation in females.
If you’re pregnant, cannabis may harm your unborn baby
Research suggests that using cannabis regularly during pregnancy could affect your baby’s brain development.
Regularly smoking cannabis with tobacco increases the risk of your baby being born small or premature.
Cannabis increases your risk of cardiovascular disease and stroke
If you smoke it regularly for a long time, cannabis raises your chances of developing these conditions.
Research suggests it’s the cannabis smoke that increases the risk, not the active ingredients in the plant itself.
Does my age affect my risks?
Your risk of harm from cannabis, including the risk of schizophrenia, is higher if you start using it regularly in your teens.
One reason for this is that, during the teenage years, your brain is still growing and forming its connections, and cannabis interferes with this process.
Does cannabis have medicinal benefits?
Cannabis contains active ingredients called cannabinoids. Two of these – tetrahydrocannabinol (THC) and cannabidiol (CBD) – are the active ingredients of a prescription drug called Sativex. This is used to relieve the pain of muscle spasms in multiple sclerosis.
Another cannabinoid drug, called Nabilone, is sometimes used to relieve sickness in people having chemotherapy for cancer.
Trials are under way to test cannabis-based drugs for other conditions including cancer pain, the eye disease glaucoma, appetite loss in people with HIV or AIDS, and epilepsy in children.
We will not know whether these treatments are effective until the trials have finished.
Trying to give up?
If you need support with giving up cannabis:
- see your GP
- visit Frank’s Find support page
- call Frank’s free drugs helpline on 0300 123 6600
- see Drugs: where to get help
You’ll find more information about cannabis on the Frank website.
Page last reviewed: 31 October 2017
Next review due: 31 October 2020
How cannabis (marijuana, weed, dope, pot) affects you, the risks and where to find help if you're trying to quit.
Cannabis can be smoked, eaten and vaped – and is the UK’s most widely-used illegal drug
How it looks, tastes and smells
What does it look like?
Soft black resin, furry green leaves and hard brown lumps, cannabis can look very different depending on its type – but it all comes from cannabis plants.
You’re most likely to come across these types:
Also known as grass, weed is made from drying out the leaves and flowering parts of the cannabis plant. It can look like dried herbs and is usually brownish-green in colour.
This is the name given for particular strains of grass that are very strong. Skunk’s become very popular in recent years and is often bright, pale or dark green in colour and covered in tiny crystals.
Not nearly as common as it used to be, hash (or hashish) is made from the resin of the cannabis plant and can be black, brown, soft or hard – depending on the type.
This is a dark, sticky and honey-coloured substance that’s much less common than other types.
These are highly concentrated forms of cannabis that are extracted using butane. They come in a solid form known as ‘dab’ or ‘shatter’ and can be used as e-liquids in vape pens.
What does it taste/smell like?
Cannabis has a musky, sweet smell. Some of the more potent types of cannabis can have a stronger smell, but this isn’t a reliable guide to the strength of any particular batch.
How do people take it?
In the UK, most people mix it with tobacco and roll it into a cannabis cigarette known as a spliff or joint. Some people don’t use tobacco at all and make weed-only spliffs – either because they prefer it that way or to avoid becoming dependent on nictotine.
Users do this mix by mixing the drug with tobacco and putting it in a pipe, lighting it, and then inhaling the smoke through water out of a large tube. There are many types of bongs, and not everyone uses tobacco. Like with joints, using tobacco in bongs increases the risk of nicotine dependence.
Eat and drink it (edibles)
People do this by mixing it into cakes (hash brownies), tea, yoghurt or sweets (gummies/lollipops). The amount of cannabis in these products can vary greatly and sometimes other harmful drugs are added too. The effects of consuming edibles are unpredictable and it can be very easy to accidentally take a larger dose than you wanted to.
This method has become more popular in recent years. Most people use a vapouriser which heats the cannabis, rather than burning it. Very little is known about the health impact of vaping cannabis.
Smoking cannabis with tobacco increases the risk of becoming dependent on nicotine. To avoid this, don’t use tobacco in bongs and spliffs.
How it feels
How does it make you feel?
The effects of cannabis can vary massively. Some people say feeling ‘stoned’ makes them feel chilled out and happy in their own thoughts, while others say it makes them giggly and chatty. But it can also make people feel lethargic, unmotivated and some people become paranoid, confused and anxious.
The sort of experience you have depends on a lot of thinks like;
- the kind of person you are (e.g. outgoing or shy)
- the mood you’re in, (if you’re feeling down it will probably make you feel worse)
- the environment you’re in (you’re more likely to feel paranoid or anxious if you don’t feel comfortable where you are or if you’re with people you don’t trust)
- how much THC it has (the main psychoactive compound in cannabis)
- how much CBD it has (which is thought to make users less likely to feel anxious and paranoid)
- how much you take
- how often you take it
Cannabis changes how you think and some people say it gives them a different perspective on things. It does affect your judgement though and people often think conversations or thoughts they have (whether good or bad) are much more deep or important when they’re stoned than they would do normally.
It can also make you hungry, known as having ‘the munchies’, or make you feel sick, known as ‘a whitey’. It can make you feel drowsy or sleepy and can give you the sense that time is slowing down.
THC & CBD
The hallucinogenic effects of cannabis are mainly due to a compound in cannabis called THC (tetrahydrocannabinol).
The other important compound in cannabis is CBD (cannabidiol). Skunk and other forms of strong cannabis contain high levels of THC but very little, or no, CBD.
It’s thought that CBD can balance out some of the effects of THC and make users less likely to feel anxious and paranoid. You can’t tell from looking or smelling cannabis whether there’s a balance of CBD and THC in it, but in general, hash may have more CBD than skunk.
How does it make people behave?
Cannabis can make some people giggly and chatty, and other people paranoid, confused and anxious – it really depends on the type of person taking it and the circumstances they take it under.
Experience mild hallucinations if they take particularly strong cannabis.
Become lethargic and unmotivated.
Have problems concentrating and learning new information. This is because studies suggest that cannabis effects the part of the brain we use for learning and remembering things.
Perform badly in exams. Because cannabis impacts the part of the brain we use for learning and remembering things, regular use by young people (whose brains are still developing) has been linked to poor exam results.
How long the effects last and the drug stays in your system depends on how much you’ve taken, your size, whether you’ve eaten and what other drugs you may have also taken.
To kick in:
When smoked, it normally takes a minute or two to feel stoned. If you eat cannabis, it can up to an hour.
How long it lasts:
This depends on how much you smoke. Generally, the effect is strongest for about 10 minutes to half an hour after smoking cannabis, but if you smoke a lot, you may still feel stoned for a couple of hours. If you eat cannabis, the peak effects can last for 2 to 4 hours, and there may even be a few more hours before the effects wear off completely.
People may still feel the effects the next day, particularly after a heavy session.
How long will it be detectable?
If you’ve used cannabis as a one-off, it will show up in a urine test for around 2 to 3 days afterwards.
However, this can go up to a month for regular users.
How long a drug can be detected for depends on how much is taken and which testing kit is used. This is only a general guide.
Physical health risks
Smoking cannabis can;
- make you wheeze and out of breath
- make you cough uncomfortably or painfully
- make your asthma worse if you have it
There’s been less research on it but smoking cannabis is likely to have many of the long term physical health risk as smoking tobacco (even if you don’t mix the cannabis with tobacco). So smoking cannabis can also;
- increase the risk of lung cancer
- increase your heart rate and affect your blood pressure, which makes it particularly harmful for people with heart disease
- reduce your sperm count if you’re male, affecting your ability to have children
- suppress your ovulation if you’re female, affecting your ability to have children
- increase the risk of your baby being born smaller than expected if you smoke it while pregnant
Mental health risks
Using cannabis can:
- affect your motivation to do things
- impair your memory so you can’t remember things or learn new information
- give you mood swings
- disturb your sleep and make you depressed
- make you anxious, panicky, or even aggressive
- make you see or hear things that aren’t there (known as hallucinating or tripping)
- cause hours (or days) of anxiety, paranoia and hallucinations, which only settle down if the person stops taking it – and sometimes don’t settle down at all
- cause a serious relapse for people with psychotic illnesses like schizophrenia
- increase your chances of developing illnesses like schizophrenia, especially if you have a family background of mental illness and you start smoking in your teenage years
What is cannabis cut with?
Lots of things. Dealers cut hash with similar-looking substances or heavy materials to increase the weight of the drug and make a bigger profit.
Although not all cannabis is cut, it’s very hard to know when it is or isn’t – so you could be smoking, eating or vaping chemicals from all sorts of unknown substances, including pesticides used when growing the cannabis.
Tobacco is often mixed with cannabis, for making joints or smoking bongs. If you mix cannabis with tobacco you’ll be taking on the same risks you get from smoking tobacco.
These are: addiction to nicotine (the drug in tobacco), coughs, chest infections and in the longer-term, cancer and heart disease.
Is it dangerous to mix with other drugs?
Yes, any time you mix drugs together you take on new risks.
For example, if you drive when stoned or high you double your chances of having a fatal or serious injury car crash, but if you drive after mixing cannabis with alcohol, you’re 16 times more likely to crash.
Smoking or vaping cannabis with tobacco increases the risk of becoming addicted to nicotine which is the addictive drug in tobacco.
Can you get addicted?
Yes. Heavy cannabis users often get cravings and find it hard not to take the drug – even when they know it’s causing them physical, mental or social problems.
When heavy users do try to stop they can:
- feel moody and irritable
- feel sick
- find it hard to sleep
- find it hard to eat
- experience sweating and shaking
- get diarrhoea
If you roll your spliffs with tobacco, you’re also at risk of getting addicted (or staying addicted) to nicotine.
This is a Class B drug, which means it’s illegal to have for yourself, give away or sell.
Possession can get you up to 5 years in prison, an unlimited fine or both.
Supplying someone else, even your friends, can get you up to 14 years in prison, an unlimited fine or both.
Like drink-driving, driving when high is dangerous and illegal. If you’re caught driving under the influence, you may receive a heavy fine, driving ban, or prison sentence.
If the police catch people supplying illegal drugs in a home, club, bar or hostel, they can potentially prosecute the landlord, club owner or any other person concerned in the management of the premises.
Additional law details
Cannabis is different to other Class B drugs as it comes under the discretionary warning scheme.
This means that a police officer can choose to issue you with a street warning only (which doesn’t form a criminal record, though it will be recorded), so long as:
- you’re in possession of a small amount of cannabis only, and for your personal use
- it’s the first time you’ve been caught with an illicit drug and you have no previous record of offence
- you are compliant, non-aggressive and admit that the cannabis is for your own use only
If you’re caught with cannabis and it’s your second offence, the police can issue with a fixed-term fee notice, which is an on-the-spot fine for £80.
As long as you pay that within 21 days, there’s no criminal record. If there’s a third occasion, you will be arrested and taken to the police station.
The main active chemical in Cannabis (Weed) is THC which can have various effects on the brain. Find out the effects, the risks and the law from FRANK.