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What is it?

Cannabis (aka weed) is a cannabinoid drug that is found in the Sativa plant which contains THC (delta9 tetrahydrocannabinol, which sounds more like a Twitter handle tbh). THC is the drug that makes you feel high.

It is usually found as dried leaves and can have a very strong, sweet smell, but can appear as a crumbly, brownish resinous substance called ‘hash’, or as a very potent oil called ‘hash oil’. It is also known as pot, Mary Jane, MJ, za, dope, gunja, joint, doobie, puff, cones, choof, mull, and 420.

Cannabis is most commonly smoked, but it can be eaten or vaporised. The dried leaves and flowers of the cannabis plant are most often smoked in a joint (sometimes mixed with tobacco) or in a bong. Hash is usually mixed with tobacco to be smoked or baked into desserts like cookies and brownies. Hash oil is applied in liquid form to the tip of a joint or cigarette. Concentrates of cannabis can be vapourised (vaped) in small quantities, mainly due to its high THC content.

What are the effects?

When smoked, the effects of cannabis can be felt immediately, and last for 1-3 hours.

  • Feelings of relaxation and euphoria
  • Spontaneous laughter and excitement
  • Increased sociability
  • Increased appetite
  • Dry mouth

  • Memory impairment
  • Slower reflexes
  • Bloodshot eyes
  • An increased heart rate
  • Mild anxiety and paranoia

  • Reduced cognitive functioning (‘brain fog’, memory loss, etc.)
  • Sore throats, asthma, bronchitis (when smoked, and if used with tobacco, there are a separate set of longer term effects)

It is important to note that due to the psychoactive properties of cannabis, people with a personal history or familial history of serious mental illnesses such as schizophrenia or bipolar disorder should refrain from using cannabis. Otherwise, using cannabis may result in a worsening of or the development of these mental illnesses. Some of these symptoms of psychosis may include delusions, hallucinations, and changes in visual and auditory perception.


It’s impossible to overdose on weed, but it’s easy to overdo it. If someone is acting unusual or in case of an emergency call 000.

Mixing with other drugs

The effects of mixing weed with other drugs – including over the counter or prescribed medications can be unpredictable. While there are no highly dangerous interactions between weed and other drugs, there are a range of unsafe interactions to be cautious of, and they can be found at TripSit.

HIV Medications

The interactions between weed and antiretroviral medications are not well known. There’s currently no evidence to suggest that weed use directly reduces the efficacy of antiretroviral medications. If some new research comes to light, then we’ll update this section and let you know.

We did find that certain antiretroviral medications can increase or decrease the effects of weed, including Efavirenz, Etravirine, Maraviroc, Cobicistat and most protease inhibitors. Chat with an HIV specialist about using weed when taking HIV medications.

The interactions between alcohol and PrEP and PEP are not well known. There’s currently no evidence to suggest that alcohol use directly interacts with these medications or reduces their efficacy. We’ll keep looking and update you if any new research comes to light.

To learn about the interactions between specific HIV medications and alcohol head to Liverpool HIV Drug Interactions Checker.


There’s currently no evidence to suggest that weed use directly reduces the efficacy of HRT. We’ll keep looking and update this information if something new comes to light.

The interactions between weed and HRT are not well known. Progesterone and Cyproterone Acetate can have sedative effects, so we may be particularly tired, fatigued or sleepy during or after taking weed. Progesterone can also contribute to an inflammation of the airways and potentially increases the risk of asthma, which is then compounded by smoking.

Oestradiol and smoking tobacco may contribute to deep vein thrombosis, so mixing tobacco and weed is something to chat with a healthcare professional about to help manage and mitigate the risk.

If mixing weed with tobacco, then it’s best to know that both testosterone and smoking tobacco can contribute to a condition known as polycythaemia. This may feel like fatigue, weakness, dizziness, or shortness of breath. Chat with your doctor to keep an eye out during any blood tests.

For more information about weed, head to ADF or TripSit.

The information given on this page is not medical advice and should not be relied upon in that way.