Which long-term effects are documented?
The long-term effects of cannabis include changes in mental health, the brain, the respiratory tract and the heart and circulation. BIÖG and the drugcom lexicon make specific statements on this. These include a higher occurrence of psychosis, dependence in about one in eight people who use cannabis, and memory problems with long-term use. This overview sorts the most important points and shows what you can take from them for yourself.
Psychological consequences
The BIÖG page describes that people who use cannabis get psychosis more often than people who do not. Drugcom adds that the psychosis risk rises with the intensity of use, and BIÖG names cannabis with a THC content above 10 percent as an additional factor. Causation is therefore unproven. Drugcom writes that there is no independent “cannabis psychosis”, though cannabis is considered a possible stress factor where susceptibility already exists.
In addition, psychological dependence can develop with long-term use. BIÖG names roughly one in eight people who use cannabis as dependent. Drugcom writes that a physical component can also develop, which is weaker than with alcohol or heroin, yet can be very unpleasant.
Brain and memory
BIÖG describes memory problems and difficulties with concentration as a possible consequence. Drugcom speaks of poorer learning and memory performance in regular users. BIÖG links this to the danger for the young brain, whose development cannabis can disrupt. Drugcom states that, according to the current state of research, substantial brain damage is probably not to be assumed, and that anyone who stops can expect brain performance to improve quickly. There is, however, convincing evidence that an early start has lasting impairments on cognitive performance.
The article How does cannabis affect memory and school qualifications? deepens this point with regard to school and training.
Lungs and airways
Cannabis is often smoked together with tobacco. Drugcom writes that for cannabis mixed with tobacco, the same risks apply as for tobacco smoking. BIÖG adds that the tobacco mixed into joints increases the risk of lung cancer later on. There are also indications of a higher risk of lung damage such as chronic respiratory complaints, coughing and shortness of breath. Drugcom emphasises that clear proof of cancer caused by cannabis smoke alone is still outstanding.
Drugcom writes that all inhaled foreign substances burden the airways, and that cannabis smoke contains roughly the same amount of tar as tobacco smoke. The article Does smoking cannabis harm the lungs? explains the connections in more detail.
Heart and circulation
The BIÖG page describes that cannabis can damage the cardiovascular system, for example through cardiac arrhythmias and vascular damage. Drugcom cites study results that suggest an increased risk of heart attack in the first hour after use, and a possibly life-threatening overload of the heart in people with pre-existing conditions. Further studies are needed. Anyone who knows about heart problems should therefore be especially careful and speak with a doctor. More on this is in the article Does cannabis affect the heart and circulation?.
Age and frequency of use
The BIÖG page summarises: the longer and more often you use, and the younger you are, the more dangerous it becomes for health. According to BIÖG, the risk of becoming dependent rises if you use once or several times a week. The article Does the harm depend on the age of starting? deepens this point.
Do damages remain after stopping?
According to drugcom, whether small impairments remain after stopping is not clearly settled scientifically. In young people, it is open whether the brain recovers completely. The article Do damages remain after stopping? takes up the question.
What you can take from this
The consequences described are a reason to check your own use honestly. Pay attention to frequency and amount, to age and to warning signs such as poorer performance or lasting mood swings. If you are unsure, counselling helps.
What “one in eight” means
The BIÖG figure that roughly one in eight people who use cannabis becomes dependent is an average value. No individual risk for you personally can be read from it.
Dependence does not show only in the amount. Drugcom describes that those affected feel they can no longer manage without cannabis. According to drugcom, neither amount nor frequency plays the decisive role; what matters is whether use has had negative consequences. The article Does cannabis cause psychological dependence? deepens this point.
Taking health changes seriously
Lasting complaints are discussed with a doctor, especially if they persist for a long time.
If you regularly have respiratory complaints, have them clarified medically. BIÖG names coughing and shortness of breath as possible consequences, and you can openly raise your use during this.
What you can do now
- Check how often and in which situation you use.
- Speak with a doctor if you have heart or breathing problems.
- Use a counselling service for an honest assessment of your use.
- If you notice warning signs, get in touch early and do not wait.
For a first phone conversation, you can reach the Sucht & Drogen Hotline on 01806 313031 (calls are charged, daily from 8 am to midnight). In an acute danger, call the emergency number 112.
Frequently asked questions
What long-term effects does cannabis have?
BIÖG names a higher occurrence of psychosis among people who use cannabis, without causation being proven. According to BIÖG, roughly one in eight people becomes dependent. With long-term use, drugcom says learning and memory performance suffer, but anyone who stops improves quickly. Tobacco mixed into joints increases the risk of lung cancer. Cardiac arrhythmias and vascular damage are also named. The longer and more often someone uses, and the younger they are, the greater the health risk.