Cannabis and Young People: What Schools Need to Know About the Law, Risks, and Safeguarding Obligations

The Scale of the Problem

NHS figures consistently show cannabis as the most widely used drug among 11–15 year olds in England, with around 6.6% of secondary-age pupils reporting use in the past year — a figure that rises significantly for older secondary pupils and those who are excluded, looked after, or at risk of exploitation.^[1]

The cannabis available in 2025 is not the same substance as in previous decades. The Advisory Council on the Misuse of Drugs (ACMD) has repeatedly highlighted that average THC concentrations in UK cannabis have more than doubled since the early 2000s — with illicit market products frequently containing 20–30% THC, compared to 4–6% in traditional herbal cannabis.^[2] This dramatically increases the risk of psychosis, dependence, and acute adverse effects.

The Law: What Every DSL and Parent Needs to Know

• Cannabis is a Class B controlled substance under the Misuse of Drugs Act 1971. Possession carries up to 5 years imprisonment; supply carries up to 14 years.
• There is no "caution threshold" in law — a young person found in possession at school can be prosecuted. In practice, many police forces use cannabis warnings for first-time possession, but this is discretionary and should not be assumed.
• Schools that discover cannabis on premises must report to police. Confiscating the substance without reporting is not appropriate and may constitute an offence by the school.
• Vaping cannabis — using a vaporiser device loaded with cannabis concentrate or oil — is increasingly common. It has no smell and is easily concealed. A child using a vape device on school premises may be using cannabis, not nicotine.

Mental Health Risks and the Adolescent Brain

The relationship between adolescent cannabis use and mental health is now well established. Key evidence:

• Psychosis risk: Daily cannabis use in adolescence is associated with a 4-fold increase in the risk of psychosis in later life, rising to 5-fold for high-potency cannabis. The risk is greatest for those who begin use before age 15.^[3]
• Depression and anxiety: Regular adolescent cannabis use is associated with increased rates of depression and anxiety in young adulthood — independent of pre-existing mental health conditions.
• Cognitive effects: The developing brain is particularly vulnerable. Memory, attention, and executive function can all be affected — with some research suggesting these effects persist into adulthood when use begins in early adolescence.

DSL Response: What to Do When Cannabis Is Found or Disclosed