How harmful is using weed?

The use of cannabis (marijuana or “weed”) is a topic surrounded by many myths on both sides of the spectrum. While some consider it a completely harmless herb, others see it as a gateway to hard drugs and a sure path to mental health problems. The truth, as usual, lies somewhere in the middle and is much more complex.

Not every user is the same: Context is crucial

Before we dive into specific risks, it's important to emphasize that harmfulness varies dramatically depending on the method of use.

• Age: The brain develops roughly until the age of 25. Use during adolescence carries significantly higher risks than use in adulthood.

• Frequency and dose: Occasional recreational use on weekends has a different impact than daily chronic use of high doses from morning to evening.

• THC potency: Today's marijuana is often much stronger than it was 30 years ago. High concentrations of THC (the psychoactive component) increase the risk of unwanted psychological reactions and addiction.

• Method of consumption: Smoking (joints, bongs) brings risks associated with combustion, which are absent—or different—in other methods (vaporization, edibles).

The scientific verdict is clear: Cannabis is not a risk-free substance. How harmful it is depends, however, on several key factors such as the user’s age, frequency of use, potency (THC content), and method of consumption.

1 Impact on the brain and mental health

This is the area where science identifies the most serious risks, especially for young people and individuals predisposed to mental disorders.

Risks for the developing brain (adolescents)

The human brain undergoes significant “reconstruction” during adolescence and early adulthood. The endocannabinoid system, to which THC binds, plays a key role in this development.

• Developmental disruption: Studies suggest that regular marijuana use during adolescence can disrupt the development of white matter, affecting communication between different parts of the brain.

• Cognitive function and IQ: Long-term and intensive use that begins at a young age is associated with measurable declines in cognitive function, including poor memory, reduced attention, and in some studies even a slight drop in IQ, which may not fully recover even after cessation.

Psychosis and schizophrenia

There is a strong and proven link between cannabis use and psychotic disorders.

• Trigger, not sole cause: Cannabis alone is unlikely to cause schizophrenia in someone with no predisposition. For individuals with genetic vulnerability, however, use (especially of high-THC cannabis) may act as a catalyst and accelerate the onset of the illness or worsen its course.

• Acute toxic psychosis: Even in healthy individuals, a high dose of THC can trigger a temporary psychotic state characterized by paranoia, delusions, and hallucinations. This state usually fades as the substance wears off, but it is highly unpleasant.

Anxiety and depression

The relationship here is bidirectional. Some people use cannabis for anxiety relief (self-medication), but for many others—especially at higher doses or with chronic use—cannabis can trigger or worsen anxiety and panic attacks. Chronic users also show higher rates of depression, although causality is not always entirely clear.

2 Physical health

If cannabis is consumed by smoking (still the most common method), it carries similar risks to smoking tobacco.

• Respiratory damage: Marijuana smoke contains many of the same carcinogens, tar and irritants as tobacco smoke. Marijuana smokers often suffer from chronic bronchitis, cough, increased mucus production and more frequent respiratory infections.

• Vaporization: Vaporization (heating the herb without combustion) is generally considered less harmful to the lungs than smoking, but it is not completely risk-free. Vaporizing liquid extracts of unknown origin may carry risks associated with added chemicals.

Note on overdose: Unlike opioids or alcohol, a fatal overdose from cannabis alone is practically impossible, because it does not affect the breathing center in the brainstem. However, this does not mean one cannot “overdose” into a state of extreme discomfort (a “bad trip”).

3 Addiction and impact on everyday life

The myth that marijuana does not cause addiction has been scientifically disproven.

Cannabis use disorder

Yes, it is possible to become addicted to cannabis, both psychologically and physically. It is estimated that approximately 9% of people who try cannabis develop an addiction. This number increases to around 17% for those who start during adolescence, and up to 25–50% for daily users.

Symptoms of dependence and withdrawal include:

• Irritability, mood changes and anxiety when stopping use.
• Sleep disturbances and vivid dreams.
• Reduced appetite.
• Strong craving (craving) and the inability to cut down despite negative consequences.

Motivation and memory (amotivational syndrome)

Chronic and heavy use is often associated with the so-called amotivational syndrome, meaning a state of apathy, reduced interest in achieving goals, work or study. Although this term is sometimes questioned as oversimplified, impaired short-term memory and concentration under the influence of the substance are undeniable, and in chronic users these issues can persist even in a sober state.

Summary: When does the risk increase significantly?

Cannabis use is not equally dangerous for everyone. The risk of negative health effects increases dramatically in the following cases:

1. Starting use before the age of 18–20 (risk for brain development).
2. Daily or almost daily use (risk of addiction and cognitive decline).
3. Using products with extremely high THC content (risk of psychosis and anxiety).
4. Personal or family history of psychotic disorders (high risk of triggering illness).
5. Smoking as a method of consumption (risk for the lungs).

In conclusion, although occasional cannabis use may not pose a major health problem for many adults, it is a psychoactive substance with real risks, especially for young people and vulnerable individuals. Downplaying these risks is not appropriate.

✔ Recommendations in conclusion

If you are looking for potential health benefits of cannabis, but also want to avoid negative effects of “weed,” then CBD is a clear choice. Why?

• No intoxication: With CBD you will not experience a “high” because it is non-psychoactive. You remain sober, functional, and clear-headed. There is no need to worry about paranoia or loss of control.

• Zero risk of addiction: Unlike THC, CBD does not create physical or psychological dependence.

• Safer for mental health: CBD does not increase the risk of psychosis or anxiety disorders, and is often sought for its anxiolytic (anxiety-reducing) effects.

Disclaimer: This article is for informational purposes only and does not replace professional medical advice. When handling any cannabis substances, always ensure that you act in accordance with the currently applicable legislation in your country or region.