Cannabis and Health — Understanding Effects, Risks, and Patterns of Use
What cannabis is
Cannabis products contain several active chemicals, most commonly THC and CBD. THC is responsible for the intoxicating “high” and alters perception, attention, and judgement. CBD does not cause intoxication but still affects body systems. Products differ widely in strength, composition, and quality, which means effects can vary significantly between people and between products.
How cannabis affects the body and mind
Cannabis can affect attention, memory, coordination, and reaction time. Many people notice slower thinking, reduced concentration, and impaired judgement for hours after use. These changes are particularly important for safety-critical activities such as driving, riding, operating machinery, or performing complex work tasks. Effects may last longer than expected, especially with stronger products.
Unpleasant or distressing reactions
Some people experience anxiety, panic, paranoia, nausea, dizziness, or a racing heartbeat. These reactions can be frightening even when they resolve without harm. Higher-potency products, unfamiliar formulations, or unexpected strength increase this risk. Combining cannabis with alcohol or other substances further increases unpredictability and side-effect burden.
Patterns of use and dependence
With repeated use, tolerance often develops, meaning more cannabis is needed to achieve the same effect. Some people develop dependence, where reducing or stopping use leads to cravings, irritability, sleep disturbance, or low mood. Dependence reflects predictable brain adaptation, not a personal failing. Recognising early patterns makes change easier.
Mental health and life stage considerations
Cannabis affects people differently depending on age, mental health history, and life circumstances. Regular use is associated with poorer mental health outcomes in some individuals, particularly younger people whose brains are still developing and those with a personal or family history of mental illness. For some, cannabis also interferes with motivation, learning, memory, and daily functioning.
Route of use and physical health
Smoking cannabis exposes the airways to irritants and fine particles, contributing to cough, chest symptoms, and lung irritation. Vaping and edible products avoid smoke exposure but carry other risks, including delayed onset and longer-lasting effects that make impairment harder to predict. “Natural” does not mean harmless, and labels do not always reflect actual content or potency.
How your GP can help
If cannabis use raises concerns for your health, mood, sleep, or functioning, your GP provides a safe, non-judgemental space to talk. Care focuses on understanding patterns of use, risks relevant to your situation, and support options if you want to reduce or change use. Conversations are personalised and confidential.
Understanding cannabis helps you make informed decisions rather than reactive ones.
This article provides general health information only and does not replace medical advice. Please speak with your GP for personalised care.