Handouts

The active ingredients. Cannabis contains many cannabinoids; the best known are THC and CBD. THC gets you high, CBD does not. In the fresh plant, THC is mostly present as THCA; it only becomes THC when heated. Marijuana is the dried flowers, hashish is the pressed resin. How much THC they contain varies widely.

How THC works. The body has its own cannabinoid system. THC docks onto its receptors; the CB1 receptors are found mainly in the brain. In the reward system, THC indirectly releases more dopamine. That explains the high and also why cannabis can be addictive. Among other things, THC affects memory and emotions, coordination and sense of time, and heart rate and digestion.

What the effect depends on. THC content, amount, form of use, state of mind and surroundings. Many people experience relaxation and a lifted mood. Restlessness, anxiety, panic and distorted perception are just as possible, especially with a lot of THC or when someone is not in a good state.

How long it lasts. Smoked or vaporised, the effect starts almost immediately, peaks after about a quarter of an hour and has largely worn off after two to three hours. Eaten or drunk, it comes on with a delay, often suddenly, and is hard to predict.

In the body. Dry mouth, red eyes, a faster heartbeat, dizziness and the munchies are common. Concentration, memory and reaction time decline during the high. That increases the risk of accidents on the road and at work.

How long cannabis can be detected. Breakdown products in urine: about three days after a single use, ten to 15 days with daily use, and over 30 days with heavy long-term use. The figures vary widely.

While it is working. Memory, attention and motor control work less well. According to reviews, the risk of a road accident rises to 1.25 to 2.66 times, and even more with alcohol. Restlessness, anxiety, panic and confusion are more common with little experience and a lot of THC. The pulse rises. Studies point to a higher risk of heart attack in the first hour, especially with pre-existing conditions; the data are limited.

With frequent use over a longer period.

• Dependence: about one in eleven people who have ever used cannabis develops a cannabis use disorder. From weekly use onwards, the risk rises markedly.
• Psychosis: the risk rises with the intensity of use, compared with people who do not use, to 1.4 to 2 times with occasional use and 2 to 3.4 times with intensive use. Vulnerable people are particularly at risk, and a lot of THC is particularly risky.
• Airways: people who smoke cough more often and more often have chronic bronchitis. Tobacco does additional harm.
• Memory: regular use makes it worse; after stopping, the impairments largely recede.
• Anxiety and depression: slightly higher risk; whether cannabis is the cause is unclear.
• Synthetic cannabinoids, which can be mixed into products of unknown origin, have hardly predictable effects; there have been deaths.

Reducing the risks. The safest choice is not to use cannabis. People who do use it can reduce the risks considerably. The international guidelines for lower-risk use, which the BIÖG recommends to adults, say: start late or not at all, less THC, do not smoke and no tobacco, be careful with edibles, rarely rather than daily, take breaks, know where it comes from, do not mix, do not drive. It is riskiest when several things come together, such as starting early, frequent use and a lot of THC.

The brain is rebuilding. In adolescence and young adulthood, new connections form and unused ones are removed. The frontal lobe, which controls planning and self-control, matures last. The Federal Ministry of Health gives an age of about 25 up to which the brain is particularly vulnerable. And that is exactly when 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. Among 12- to 17-year-olds, use has been falling slightly since 2019.

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 drop out of school more often on average. Whether cannabis is the cause 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.

What the law says. Under 18, possession, cultivation and purchase are prohibited (§ 2 KCanG). No one may use cannabis in the immediate presence of minors, nor within sight of schools, playgrounds, children’s and youth facilities and sports grounds (§ 5). For 18- to 20-year-olds, the law limits what cultivation associations may pass on to 30 grams a month with no more than 10% THC (§ 19 para. 3). Anyone over 21 who gives cannabis to minors must as a rule expect three months to five years in prison (§ 34). If minors are caught with cannabis, the police inform the parents and, if necessary, the youth welfare office; the aim is early intervention (§ 7). At home, cannabis must be stored safely (§ 10).

For some people, cannabis is particularly risky. For them the recommendation is: do without.

• Pregnancy, breastfeeding, wanting a child. THC reaches the baby through the umbilical cord. Smoking during pregnancy is linked to lower birth weight; a large review found higher risks of premature birth and growth restriction. No safe amount is known. THC passes into breast milk; in one study it was detectable for up to six days. Cannabis can reduce fertility.
• Psychosis in the family. Anyone whose parents or siblings have had a psychosis should do without. Anyone who has already had a psychosis risks a poorer recovery and more relapses. With bipolar disorder, regular use goes along with more manic symptoms.
• Heart and circulation. Pulse and blood pressure can rise straight after use; with pre-existing conditions, the heart can be overloaded.
• Under 25. The brain is still maturing, and the risk of dependence and psychosis is higher.
• Addiction, including a past one. Switching to another substance risks a relapse.
• Regular medication. THC and CBD slow down liver enzymes that break down many medicines. Antidepressants can work more strongly, and with blood thinners the risk of bleeding can rise. Best discussed with a doctor or pharmacist.
• Alcohol on top. The effects reinforce each other: drowsiness, confusion, nausea, up to loss of control.

Person, substance, setting. Experts describe addiction in terms of three sides that interact: the person, with the way they deal with feelings and problems; the substance, with its effect and availability; and the setting of family, friends, school and work. No single side explains a dependence on its own.

What happens in the brain. THC acts on the reward system. If this happens often, the brain becomes less sensitive, and the same effect takes more (tolerance). After the high, restlessness and irritability can follow. Over time, people often use to get rid of this discomfort. Anyone who uses cannabis to dampen anxiety, anger or sadness is at higher risk.

Risk factors. Frequency of use (the strongest single factor), starting early, especially before 16, a lot of THC, tobacco at the same time, psychological stress, lack of support, drastic life events, a circle of friends in which almost everyone uses. Risk factors describe probabilities, not a prediction.

What protects. Confidence, the feeling of being able to make a difference, being able to tackle problems, stable relationships and a role in training or work.

How experts classify it. According to the DSM-5, a cannabis use disorder is present if at least two of eleven criteria apply within twelve months: two to three count as mild, four to five as moderate, six or more as severe. The stages range from occasional use through risky use and harmful use to dependence; the transitions are fluid.

Withdrawal. Almost one in two people who use regularly know withdrawal symptoms: nervousness, sleep problems, little appetite, irritability, anxiety or low mood. They usually start one to three days after the last use and are strongest in the first week. Most subside after two to three weeks; sleep problems and low mood can last longer.

Problematic use usually develops gradually. Experts use eleven criteria from the DSM-5. In everyday language:

• Control: using more or for longer than planned; wanting to cut down but not managing it; a lot of time spent getting hold of it, using and recovering; strong cravings.
• Everyday life and relationships: responsibilities are left undone; using despite arguments; hobbies, friendships and sport take a back seat.
• Risk: using in dangerous situations, for example before driving; carrying on despite noticeable harm.
• Body: needing more for the same effect; feeling bad without cannabis (withdrawal).

If two to three points apply within twelve months, experts speak of a mild disorder, four to five of a moderate one and six or more of a severe one. Only doctors or psychotherapists can make a diagnosis. The list helps you take an honest look.

Signs in others. Performance at school or work suddenly drops, the circle of friends changes, there are more problems at home, hobbies are given up, mood swings and withdrawal, lies or excuses. Such signs can also have other causes. They are a reason for a conversation, not a diagnosis.

How to recognise it. Anxiety, panic, confusion and paranoid thoughts, up to perceiving things that are not real; physically a racing heart, nausea, dizziness, and even a collapse is possible. With alcohol or other substances this becomes much stronger. Unpleasant states usually pass.

What to do.

• Responsive and breathing normally: stay with them, take them somewhere quiet with fresh air, talk calmly, do not leave them alone. If their skin is pale and clammy and their pulse fast, lay them down and raise their legs.
• Unresponsive, breathing normally: call 112, recovery position, check breathing regularly.
• Not breathing or not breathing normally: call 112 and start chest compressions immediately.

Call 112 immediately if someone is unconscious or has breathing problems, a seizure or severe pain behind the breastbone, or if you are unsure; with mixed use, call sooner. Tell the emergency services what was taken and give them any leftovers.

Children and edibles. If children eat cannabis or sweets containing cannabis, severe poisoning is a risk. Call the poison control centre for North Rhine-Westphalia on 0228 19240, around the clock; if the child’s consciousness is impaired or they have breathing problems, call 112 immediately. Do not make the child vomit; keep leftovers and packaging.

Repeated vomiting. After long, frequent use, cannabis hyperemesis syndrome can develop: recurring bouts of vomiting, typically eased by hot showers. Have it checked by a doctor. The only effective treatment is to stop using.

Synthetic cannabinoids and HHC. Synthetic cannabinoids can be many times stronger than THC and cannot be recognised from the outside; there have been deaths. HHC has been banned since 27 June 2024.

Limit. Anyone who drives a motor vehicle with 3.5 ng/ml THC or more in their blood serum commits an administrative offence (§ 24a StVG). For a first offence that means €500 and a one-month driving ban, €1,000 in combination with alcohol. During the probationary period and before your 21st birthday, no THC at all is allowed at the wheel (§ 24c StVG). Anyone who is not fit to drive commits a criminal offence regardless of the limit (§ 316 StGB). If there are signs of misuse or repeated offences, the driving licence authority can order an MPU, a medical-psychological assessment (§ 13a FeV).

Feeling sober is not enough. Impairments can remain after the noticeable effect has worn off. The professional societies for traffic psychology and traffic medicine recommend as a minimum: at least 12 hours after occasional smoking or vaporising, at least 24 hours if the THC content is unknown or the amount larger, more than 24 hours after edibles, usually three to five days with regular use on several days a week, and several weeks with daily use. If you are unsure, leave the car at home.

What tests show. Saliva tests serve as a preliminary test; the blood sample is what counts. In urine, breakdown products can be detected for about three days after a single use, ten to 15 days with daily use and over 30 days with heavy long-term use; in hair for months.

Where use is prohibited. In the presence of minors, in schools, on playgrounds, in children’s and youth facilities, public sports grounds and cultivation associations, in each case also within sight (up to 100 metres from the entrance); in pedestrian zones from 7 am to 8 pm (§ 5 KCanG). In NRW, using in a prohibited zone costs €50 to €500, in the presence of minors €300 to €1,000.

Possession and passing on. From 18, up to 25 grams when out and about, up to 50 grams and three plants at home (§ 3 KCanG), stored safely away from children (§ 10). Cannabis from a cultivation association may not be passed on to others, not even to adults (§ 19 para. 4).

Change takes time. People rarely change their behaviour all at once. Experts describe stages: “It’s not a problem”, “I really should, but …”, “I’m planning something”, “I’m changing something right now”, “I’m sticking with it”. Relapses are part of it. Anyone who only argues for change often achieves the opposite.

The right moment. You are both sober, it is calm, you have time, and you have thought about what you want to say. Bad times are straight after use, during an argument or with other people listening.

How to raise it.

• Use I-statements to describe what you observe: “I’m worried because I’ve noticed that you hardly go out any more.”
• Address the behaviour, not the person.
• Ask open questions, listen, let them finish. No lecturing, no diagnosis.
• Ask before you give advice.
• Expect defensiveness and do not take it personally.
• Acknowledge what is going well and offer support. The decision rests with the person.

Your limits. Say clearly what you will not go along with, and stick to it. Covering up, playing things down and taking over the other person’s tasks tend to support the use. Get support for yourself.

Help, also for family members. Addiction counselling is free, confidential and anonymous on request, even if the person concerned does not want help.

• DROBS Dortmund, Reinoldistraße 17-19, 0231 477376-0
• Social psychiatric service of the City of Dortmund, Hoher Wall 9-11, 0231 50-22534, with groups for family members
• DigiSucht: online counselling by message, chat or video, free and anonymous
• Addiction and drugs hotline (Sucht & Drogen Hotline): 01806 313031, daily 8 am to midnight, €0.20 per call