- Most claims do not stand up to scrutiny.
- Some things are unclear. When that is the case, we say so.
- Every assessment has a label: not true, not proven, cause unclear, early evidence or well established.
“Cannabis isn’t addictive.”
not true
About 9 % of all people who have ever used cannabis develop a cannabis use disorder. The BIÖG speaks of around one in eight people who use it becoming dependent. How dependence develops is explained in the module How dependence develops.
“Only at weekends, so nothing happens.”
not true
The risk of becoming dependent rises when someone uses cannabis once or several times a week. Frequency counts as a risk factor. So the weekend is no protection if it is every weekend.
“Indica makes you sleepy, sativa wakes you up.”
not proven
An analysis of almost 90,000 samples from six US states found that the labels do not reliably match the chemical composition. The researchers therefore consider advertising that sells “indica” as calming and “sativa” as energising to be unfounded.
“CBD cancels out the effect of THC.”
not true
In a controlled study, CBD in the ratios usual in products did not protect against the acute effects of THC: neither against memory problems nor against psychotic symptoms. According to the BIÖG, whether more CBD lowers the risk of psychosis in the long term is less clearly established.
“Only the tobacco in a joint is harmful.”
not true
Cannabis smoke contains about as much tar as tobacco smoke. People who smoke regularly have coughs and other respiratory problems more often. Tobacco comes on top of that: it increases the risk of lung cancer and of dependence on both substances.
“Starting young means more risk.”
well established
That is true. Being young when you first use cannabis is a particular risk factor for a cannabis use disorder. More on this in the module Why age matters.
“More THC just makes it stronger, not riskier.”
not true
The higher the THC content, the higher the risk of psychosis. According to the BIÖG, a bad trip also becomes much more likely with a high THC content.
“Too much is harmless, you just fall asleep.”
not true
It is very rare for someone to die from too much cannabis alone. But too much is still not harmless: anxiety, panic, confusion and a racing heart are possible, and anyone with a pre-existing heart or circulation condition is particularly at risk. With edibles the effect sets in late, which makes an overdose easier. For children there is an acute risk of poisoning. What helps then is explained in the module When it gets too much.
“Cannabis is a gateway drug.”
not true
Most people who use cannabis do not move on to other drugs. As early as 1994, Germany’s Federal Constitutional Court noted that the view that cannabis acts as a “pacemaker” towards harder drugs was predominantly rejected. It attributed any switch to the shared illegal market, where cannabis and hard drugs are often sold by the same people. The German Centre for Addiction Issues (DHS) today calls the theory no longer tenable. That many people who use other drugs used cannabis earlier is partly explained by shared risk factors such as predisposition, stressful experiences or stress. Research has not shown that cannabis itself contributes.
Our view: if anything deserves to be called a gateway drug, it is nicotine, caffeine and alcohol. They are legal, available everywhere and most people come across them earlier than cannabis.
“Smoking weed makes you permanently stupid.”
early evidence
When high and with regular use, it is above all memory and attention that suffer. These impairments seem to go away again after stopping. So far, only individual studies show lasting impairments, mainly when use starts in adolescence.
“Cannabis helps you sleep.”
not proven
A review of 18 studies found that cannabis mostly has a negative effect on sleep. Whether people fall asleep faster was not clear. Anyone who uses cannabis to fall asleep often sleeps worse at first after stopping.
“If I feel clear-headed, I can drive.”
not true
In a driving simulator study, almost half of the participants felt fit to drive again after an hour and a half, but drove measurably worse than the comparison group. Health Canada writes that impairment can last longer than 24 hours. What applies legally is explained in the module Road traffic and the law.
Sources
- Federal Ministry of Health (2017): summary report “Cannabis: potential and risks” (CaPRis)
- cannabispraevention.de (BIÖG): health aspects
- Smith, Vergara, Keegan, Jikomes (2022): The phytochemical diversity of commercial Cannabis in the United States, PLOS ONE
- Englund et al. (2023): Does cannabidiol make cannabis safer? Neuropsychopharmacology, entry at the University of Bath
- drugcom.de (BIÖG, 2023): recommendations for reducing the risk of psychosis from cannabis use
- drugcom.de (BIÖG): drug glossary, entry on cannabis, as of January 2026
- drugcom.de (BIÖG, 2022): can cannabis be fatal? (Rock et al. 2022)
- BIÖG (2025): information on cannabis, information sheet for members of cultivation associations
- NIDA (2024): Is marijuana a gateway drug?
- DHS and BZgA: basic information on cannabis
- drugcom.de (BIÖG, 2025): cannabis does not help with sleep problems (Costa et al. 2025)
- drugcom.de (BIÖG, 2009): sleep problems during cannabis abstinence (Bolla et al. 2008)
- drugcom.de (BIÖG, 2022): cannabis users overestimate their fitness to drive after smoking (Marcotte et al. 2022)
- Health Canada (2023): Cannabis impairment and safety risk
- Bundesverfassungsgericht, Beschluss vom 9. März 1994, 2 BvL 43/92 u. a. (BVerfGE 90, 145), Rn. 149