Discovering that a teenager is using substances – whether it's the smell of alcohol, finding a vape, or noticing that their eyes are red – produces one of the most challenging parenting moments of adolescence. The instinct ranges from panic to anger to minimisation ("I did it at that age"), and the right response is none of those.
The starting point is information: what are the actual risks, what is in the range of normal adolescent experimentation, and what patterns of use warrant serious concern? And then: what does research tell us about the parental responses that actually help?
Healthbooq (healthbooq.com/apps/healthbooq-kids) covers adolescent health and parenting teenagers.
Alcohol
Alcohol is the most widely used substance among UK teenagers. NHS Digital data shows that while the proportion of young people who drink has declined since the early 2000s, those who do drink tend to drink more heavily than previous generations of teenage drinkers. Around 44% of 15-year-olds reported having drunk alcohol in the last week in the most recent Health Behaviour in School-aged Children (HBSC) survey, compared with over 60% in the early 2000s.
The harms from adolescent alcohol use are dose-dependent and cumulative. The developing brain – particularly the prefrontal cortex and hippocampus, both still maturing through adolescence – is more vulnerable to alcohol-related harm than the adult brain. Aaron White at Duke University and others have documented that heavy drinking in adolescence is associated with impaired memory consolidation, reduced white matter development, and increased risk of alcohol use disorder in adulthood. The risk of developing alcohol dependence is substantially higher for people who begin drinking regularly before age 15 compared with those who start at 21.
The UK Chief Medical Officers advise that an alcohol-free childhood is the healthiest option and that, for those who do drink, delaying the start and reducing the amount consumed on any occasion are both beneficial.
Cannabis
Cannabis is the most commonly used illegal drug among UK teenagers. Data from the Crime Survey for England and Wales consistently shows that around 12-14% of 16-24 year olds used cannabis in the past year. Most of this use is experimental or occasional.
The evidence on cannabis and adolescent development has clarified substantially in the past decade. The most robust findings are:
Early, regular cannabis use (before age 16, several times per week) is associated with significantly increased risk of psychotic disorders in those with genetic vulnerability. The evidence – from prospective cohort studies including the Dunedin Multidisciplinary Health and Development Study in New Zealand (Caspi, Moffitt and colleagues) and Avon Longitudinal Study of Parents and Children (ALSPAC) in the UK – shows that cannabis use increases the risk of psychosis by about twofold on average, rising to around fourfold in those who carry specific variants of the COMT gene, which affects dopamine processing. This interaction between genetic vulnerability and cannabis use is one of the clearest gene-environment interaction findings in psychiatric genetics.
High-potency cannabis (skunk, with THC content often above 20-25%) carries greater risk than lower-potency cannabis. The proportion of high-potency cannabis available in the UK has increased substantially since the 2000s: research by Marta Di Forti at King's College London documented this shift and its association with psychosis risk.
Cognitive effects: multiple studies show that regular cannabis use in adolescence is associated with impairments in memory, processing speed, and attention that persist to some degree even after cessation. The effects appear greater in those who started early and used heavily, and are greatest for verbal memory.
The risk of cannabis use disorder (dependence) in those who use cannabis is approximately 9% overall, but substantially higher in those who started before 18.
Vaping and E-Cigarettes
Vaping has changed the landscape of adolescent nicotine use dramatically. In the UK, the proportion of young people who have ever vaped increased from around 5% in 2018 to around 20% in 2023, according to ASH (Action on Smoking and Health) survey data. Disposable vapes – cheap, brightly coloured, and in a wide range of flavours – have driven much of this increase, marketed in ways that clearly appeal to children and young people.
The central concern about vaping in adolescents is nicotine addiction. Most vapes contain nicotine, often at high concentrations (some disposable vapes contain the equivalent nicotine of 40-60 cigarettes). Nicotine is highly addictive, and adolescents appear to develop nicotine dependence more quickly than adults. The nicotine-free vape is a minority product; most young people vaping are inhaling significant nicotine.
Relative to cigarette smoking, vaping is probably less harmful for adults who are using it as a cessation tool. This is not the relevant comparison for adolescents, for whom the baseline should be not smoking at all. The long-term respiratory and cardiovascular effects of vaping are not yet known; the products have been available for too short a time for long-term follow-up data. There is evidence from in vitro and animal studies of airway inflammation, and case series from the US have documented severe lung injury (EVALI – e-cigarette or vaping product use-associated lung injury) associated primarily with vitamin E acetate added to illicit THC vapes but also in some cases with legal nicotine vapes.
Under the UK's Tobacco and Vapes Bill (in progress as of 2024-2025), the sale of vaping products to under-18s is illegal, and new restrictions on flavours and marketing aimed at children are planned.
What Parents Can Do
The response that research most consistently supports is open, non-judgmental conversation. Susan Ennett at the University of North Carolina has published extensively on the family factors that predict adolescent substance use: the strongest protective factors are warmth and connection in the parent-child relationship, parental monitoring (knowing where the child is and who they're with, which predicts rather than surveils), and direct communication about substance use.
Parents who respond to substance discovery with severe punishment or withdrawal of trust achieve reduced disclosure in subsequent encounters: the child learns not to tell them. Parents who respond with curiosity and concern – "tell me about it, I want to understand" – are more likely to hear about future incidents and to have a genuine influence on the behaviour.
Being honest about actual risks – rather than either catastrophising ("one joint and you'll be schizophrenic") or minimising ("it's just experimentation, everyone does it") – gives teenagers a framework they can use. When parents overstate risk, teenagers who have direct experience know they've been lied to, and this undermines trust and future communication.
Specific conversations worth having: the particular risk of high-potency cannabis; the fact that vaping is not harmless; the relationship between alcohol and impaired decision-making (rather than the abstract health consequences, which feel remote at 15); and the legal consequences of drug use.
For teenagers who are using substances regularly and whose functioning is being affected – academic decline, social withdrawal, mood changes, financial problems – a GP assessment and referral to a specialist youth substance service is appropriate. FRANK provides information and a 24-hour helpline (0300 123 6600) for young people and parents.
Key Takeaways
Substance use in adolescence is common and varies widely in its risk profile. Most young people who experiment with alcohol, cannabis, or tobacco do not go on to develop problematic use. However, the adolescent brain is at a developmentally sensitive period for substance-related harms: early regular cannabis use is associated with increased risk of psychosis and cognitive impairment; underage drinking affects brain development; and vaping is exposing a new generation to nicotine addiction. The single most protective factor against adolescent substance problems is parental relationship quality and open communication. Harsh or punitive responses are associated with reduced disclosure and worse outcomes; non-judgmental conversation is more effective.
