Cannabis use health risks

Overview

Cannabis, also known as marijuana or weed, is a plant that people use for medical or recreational reasons. Using it can come with certain health risks, both short-term and long-term. This article explains those risks in plain language.

Yes, cannabis is one of the most commonly used recreational drugs worldwide, particularly among young adults.

Anyone who uses cannabis can experience health risks, but young people, frequent users, and people with a personal or family history of mental health conditions are more likely to be affected.

Symptoms

Common symptoms

• Red or bloodshot eyes
• Increased appetite (the "munchies")
• Dry mouth
• Altered perception of time and space
• Sleepiness or lack of energy
• Anxiety or paranoia, especially with higher doses

Symptoms in children

• Difficulty learning or remembering new things
• Mood swings or irritability
• Withdrawal from family and friends
• Increased risk of mental health problems such as depression or psychosis

Symptoms in older adults

• Worsening memory or confusion
• Risk of falls due to dizziness or unsteadiness
• Interactions with medicines (such as blood thinners or sedatives)
• Increased risk of heart problems

Causes

Main causes

• Cannabis use itself is the direct cause of the health risks. The main ingredient that affects the brain is THC (tetrahydrocannabinol).
• The way you use cannabis (smoking, vaping, eating) also influences the risks.

Risk factors

• Starting cannabis use at a young age (under 16)
• Using cannabis frequently (daily or several times a week)
• Using high-potency cannabis (high THC content)
• Having a personal or family history of mental health conditions (such as anxiety, depression, or psychosis)
• Having a personal or family history of substance use disorder
• Smoking cannabis rather than using non‑smoked forms

When to see a doctor

See a doctor urgently if:

• If you or someone else has chest pain, severe confusion, or a panic attack after using cannabis.
• If you are experiencing hallucinations or thoughts of harming yourself or others.

Book a routine appointment if:

• If you are worried about your cannabis use or finding it hard to cut down.
• If you have been using cannabis regularly and notice memory problems, mood changes, or trouble at work or school.
• If you have a lung condition or persistent cough that might be related to smoking cannabis.

Diagnosis

There is no single test for cannabis-related health problems. A doctor will ask about your cannabis use, your symptoms, and your medical history. They may also use questionnaires to assess whether your use has become harmful or dependent.

Tests that may be done

• No routine lab tests are needed, but sometimes a urine or blood test can confirm recent use if required for a specific reason (such as a job or driving assessment).
• Your doctor may assess your mental health and lung function if you have related symptoms.

What to expect at your appointment

The conversation will be private and respectful. The doctor will focus on understanding your situation and offering advice or resources to help you stay healthy.

Treatment

If cannabis use is causing problems, treatment usually involves support and talking therapies. There is no specific medication to treat cannabis use disorder itself, but medicines may be used for related conditions like anxiety or depression.

Self-care at home

• Set a clear goal to reduce or stop your cannabis use.
• Identify triggers (like stress or certain friends) that lead you to use cannabis.
• Find healthy alternatives, such as exercise, hobbies, or talking to a friend.
• Join a support group or talk to a counselor.

Medical treatments

Doctors may offer counseling approaches such as cognitive behavioral therapy (CBT) or motivational interviewing to help you change your habits. If you have withdrawal symptoms (anxiety, trouble sleeping, irritability) when you stop, they can suggest ways to manage these. For mental health problems like depression or anxiety, standard treatments (therapy and/or medication) may be recommended, but your doctor will consider your cannabis use when choosing the best plan.

When is surgery considered?

Cannabis use is not a direct reason for surgery, but if you need surgery it is important to tell your surgeon about your cannabis use because it can affect anaesthesia and pain management.

Living with this condition

If you use cannabis, it helps to be aware of how it affects your daily life. Pay attention to your memory, mood, and energy levels. Consider cutting back if you notice problems with work, school, or relationships.

Lifestyle tips

• If you smoke cannabis, think about switching to non‑smoked forms (like edibles or tinctures) to protect your lungs, but be aware that these also have risks.
• Avoid using cannabis before driving or operating machinery.
• Set limits on how much and how often you use.

Diet and exercise

Eating a balanced diet and staying active can improve your overall well‑being and may help you cut down on cannabis. Exercise releases natural chemicals that boost mood and reduce cravings.

Mental health and emotional wellbeing

Cannabis can make anxiety, depression, or other mental health conditions worse, especially with regular or high‑dose use. If you notice changes in your mood or thinking, talk to a doctor.

Prevention

The only way to completely avoid the health risks of cannabis is not to use it. If you choose to use cannabis, you can reduce risks by starting later (after age 25), using less often, and avoiding high‑potency products.

Complications

If left untreated

• Developing cannabis use disorder (addiction): needing to use more, finding it very hard to stop, and it taking over your life.
• Worsened mental health: increased anxiety, depression, or even psychosis in vulnerable people.
• Lung damage if you smoke it: chronic cough, bronchitis, and possibly increased risk of lung infections.
• Memory and learning problems that persist even after you stop using.
• Financial, legal, and relationship difficulties.

Long-term outlook

The good news is that most health risks from cannabis use can be reduced or reversed if you cut down or stop. Many people successfully quit with the right support. If you are concerned about your cannabis use, reaching out for help is a positive step.

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