Why age matters

The brain reorganises itself

In adolescence and young adulthood, new connections form in the brain, unused ones are broken down and nerve pathways become faster. This affects, among others, the areas for memory, attention and impulse control. The frontal lobe, which governs planning and self-control, is the last to mature. The Federal Ministry of Health gives an age of around 25 up to which the brain is particularly vulnerable.

Yet it is precisely at this age that use is highest: among 18- to 25-year-olds, almost one in three young men used cannabis in the past year, and just under one in five young women.

Over the decades, use among young adults has risen markedly. Among 12- to 17-year-olds, by contrast, it has been falling slightly since 2019, including after partial legalisation.

What starting early means

• Dependence: Starting early, especially before 16, is a well-established risk factor.
• Education: People who start before 15 and use frequently in early adolescence are, on average, more likely to drop out of school and less likely to complete a university degree. Whether cannabis is the cause or other circumstances play a part has not been established.
• Mental health: Use in adolescence is linked to more depression and suicidal thoughts in adulthood. Here too, the cause has not been conclusively established.
• Thinking: Whether starting early permanently impairs thinking is disputed.

What the law says

• Under 18, possession, cultivation and acquisition are prohibited (§ 2 KCanG).
• Nobody may use cannabis in the immediate presence of minors (§ 5 para. 1 KCanG). Use is also prohibited in and within sight of schools, playgrounds, children’s and youth facilities and public sports facilities; a place is no longer within sight at a distance of more than 100 metres from the entrance (§ 5 para. 2 KCanG).
• For 18- to 20-year-olds, the law limits what cultivation associations may pass on to 30 grams a month, with at most 10% THC (§ 19 para. 3 KCanG).
• Anyone over 21 who gives cannabis to minors must, as a rule, expect a prison sentence of three months to five years (§ 34 KCanG).
• If minors are found with cannabis, the police inform their parents and, if necessary, the youth welfare office (§ 7 KCanG).

When young people are found with cannabis

Cannabis remains prohibited for minors, but possessing small amounts is no longer a criminal offence. The police confiscate the cannabis and inform the parents. If there are substantial indications that the child’s welfare is at risk, for example because of risky use, they also inform the youth welfare office. The youth welfare office should then work with the parents towards the young person taking part in an early intervention programme (§ 7 KCanG).

It becomes a criminal offence with larger amounts, with dealing and with passing cannabis on to others (§ 34 KCanG). Young people are criminally responsible from the age of 14 (§ 19 StGB). Juvenile criminal law then applies: it relies first on education, for example through instructions or conditions. Youth detention is also possible and, if none of that is enough, a youth prison sentence.

Since partial legalisation, early intervention programmes such as FreD have been used less often, because the justice system hardly refers young people to them any more. This is shown by the evaluation of the Act; more on this in the module Road traffic and the law. Parents do not have to wait for that: in Dortmund, Feedback (in German), the youth counselling service of DROBS, offers early intervention and advice for parents, on a voluntary, free and confidential basis.

Protecting children

At home, cannabis must be kept where children and young people cannot get to it (§ 10 KCanG). If children eat cannabis or food containing cannabis, there is a risk of poisoning.

Sources

• Bundesministerium für Gesundheit: FAQ zum Cannabisgesetz
• drugcom.de (BIÖG, 2020): Wie schädlich ist Cannabiskonsum für das Gehirn junger Menschen?
• NIDA (2020): Drugs, Brains, and Behavior. The Science of Addiction
• Bundesministerium für Gesundheit (2017): short report “Cannabis: Potenzial und Risiken” (CaPRis)
• cannabispraevention.de (BIÖG): Risiken für Jugendliche
• DHS: Cannabis, Zahlen, Daten, Fakten (Drogenaffinitätsstudie 2025, ESA 2024)
• BIÖG (2025): Elterninfo Cannabis
• BIÖG (2025): Die Drogenaffinität Jugendlicher und junger Erwachsener in Deutschland 2025, Cannabis
• Konsumcannabisgesetz (Consumer Cannabis Act, KCanG), §§ 2, 5, 7, 8, 10, 16, 19, 23, 34
• Strafgesetzbuch (German Criminal Code), § 19
• Jugendgerichtsgesetz (Youth Courts Act), §§ 5, 9 to 17
• EKOCAN (2026): Evaluation des Konsumcannabisgesetzes, 2. Zwischenbericht
• Feedback, youth counselling and addiction prevention service of DROBS Dortmund