Cannabis (also known by its many slang names including marijuana, weed, Mary Jane, pot, dope, zaza, ganja, grass etc.) is a plant originating from Central and South Asia.1 There are three recognised species of Cannabis: Cannabis sativa, Cannabis indica, and Cannabis ruderalis (commonly just called sativa, indica, and ruderalis).1 Cannabis can be consumed in a variety of ways including smoking, eating, or vaping.2 Cannabis is most commonly smoked in a joint (cigarette) or by using a bong, and is often mixed with tobacco.2,3 “Edibles” are foods (commonly cookies, brownies, or gummies) containing oils extracted from the cannabis plant.2 Cannabis can also be vaped using concentrated extracts (e.g. oil, wax, or dabs), or using dried flowers in a dry herb vape.2
The cannabis plant contains at least 65 cannabinoids, many of which are psychoactive.1 The two major cannabinoids associated with the desirable effects of cannabis are tetrahydrocannabinol (THC) and cannabidiol (CBD).1 THC is responsible for most of the psychoactive effects of cannabis (responsible for the “high”) and works by activating CB1 and CB2 receptors in the body.4 CBD, on the other hand, prevents the activation of CB1 and CB2 receptors and is thus not psychoactive, but may help to reduce inflammation, nausea and anxiety, promote sleep, and prevent seizures.4
Cannabis is still illegal in many parts of the world; however some countries have legalised cannabis for medicinal use.5 Across all states of Australia, cannabis is legal as a prescription medication.5 Some doctors, including GPs, prescribe medicinal cannabis for a variety of conditions, most commonly chronic pain.6 Medicinal cannabis is also used to treat anxiety, cancer-related symptoms (e.g. nausea, pain, and reduced appetite), epilepsy, insomnia, and multiple sclerosis (MS).6
Some parts of the world have decriminalised or legalised cannabis for recreational use, including Canada, Mexico, California, Thailand, and the Australian Capital Territory.5 In the ACT, possessing certain amounts of cannabis was decriminalised in 2019 and some penalties for possessing and growing cannabis were removed in 2020.7 People aged over 18 in the ACT can possess up to 50 grams of dried cannabis, possess up to 150 grams of fresh cannabis, grow up to two plants per person with a maximum of four per household, and use cannabis at home.7 In the ACT, it’s still illegal to smoke cannabis in public, drive under the influence of cannabis, expose children to cannabis, or grow cannabis using hydroponics or artificial cultivation.7
The effects of cannabis can depend on the mindset of the user (set) and the environment in which the person is using it (setting). The effects can also vary from person to person.
The effects of cannabis can include:1,6,8
Euphoria, mood lift.
Uncontrollable laughter, giggling.
Pain relief (analgesia).
Dry mouth (“cotton mouth”)
Forgetfulness, memory problems.
Increased heart rate (tachycardia).
The effects of cannabis also depend on the strain. Sativa strains tend to produce more of a “head high” with an energising effect, whereas indica strains tend to produce more relaxation, more pain relief, and an increased appetite.9 There are also hybrid strains which can be more like a sativa (sativa-dom), or more like an indica (indica-dom).9
The effects of smoked or vaped cannabis typically peak around 10 minutes after consumption and can last 1-3 hours.10 The effects of edible cannabis usually take longer to kick in (typically peaking 2 hours after consumption) and last much longer (up to 24 hours).10
Choosing the correct dose for cannabis can be difficult since different strains and batches vary greatly in their THC content and thus their potency. It’s always recommended to start low and go slow when dosing cannabis (that is, start with a low dose and wait before redosing). People who are new to cannabis are generally more sensitive to the effects and require a smaller dose to get high.11 Additionally, some people are simply more sensitive to the effects of cannabis in general.11
The following is a rough dosage guide for THC:11
LOW DOSE – 2.5 mg
MODERATE DOSE – 5 mg
STRONG DOSE – 10 mg
Cannabis strains can vary from below 10% to more than 25% in THC by weight.12 Sativa strains typically contain more THC than indica strains.9 A THC dosage calculator for common THC strains is available here. Unfortunately, drug checking services like CanTESTcannot measure the amount of THC or CBD present in a cannabis sample.
Cannabis Overdose and “Greening Out”
Overdosing on cannabis alone (commonly called “greening out”) is not physically dangerous and no deaths have ever been reported due to a cannabis overdose.13 However, greening out can be a very unpleasant experience, and symptoms of cannabis overdose can include:13
Increased heart rate (tachycardia).
Nausea and vomiting.
Cannabis can interact poorly with other drugs.14 Mixing cannabis with psychedelics (e.g., psilocybin mushrooms, DMT, and LSD) or stimulants (e.g., MDMA, cathinones, cocaine, and amphetamines) can increase their potency and increase the risk of anxiety and panic.14 If someone is having a bad reaction as a result of mixing cannabis with another drug, consider seeking medical attention and wait with them until they recover.
An intense experience on cannabis will likely subside after 20 minutes to a few hours.13 A nap may help to speed things up, although this is not recommended if someone has mixed cannabis with depressants such as alcohol.10 There are some other remedies for a cannabis overdose with limited scientific evidence including: eating black pepper, eating pine nuts, taking CBD, or eating lemon peels.10
While less addictive than alcohol or nicotine, people can still become dependent on cannabis.1,8 Psychiatrists call this cannabis use disorder.8 Long-term heavy cannabis use can lead to tolerance (needing to take more to get high) and withdrawal effects.8,4 These withdrawal effects can begin up to one week after stopping regular cannabis consumption and can last for up to 2 weeks depending on the frequency and intensity of use.8
The symptoms of cannabis withdrawal are not life-threatening but can include:1,8
Irritability, anger, or aggression.
If you are concerned about cannabis dependence or are experiencing the symptoms of cannabis withdrawal, consider visiting a non-judgemental health professional such as the nurse or GP at the CAHMA clinic.
Cannabis and Psychosis
Multiple studies have observed a link between cannabis use and psychosis/schizophrenia, although much is still unknown about this link.15,16 Frequent use of high-potency cannabis from a young age has been associated with a significantly earlier onset of psychosis, which can progress to a chronic psychotic disorder such as schizophrenia.16,17 In some cases, psychosis can begin 6 years earlier in people who frequently use cannabis.17 Some risk factors for the onset of psychosis in cannabis users include:16