What is THC? Effects, mechanisms, legality and precautions
THC explained: what it does, its risks, and alternatives if you're looking for an effect without getting high.
THC (tetrahydrocannabinol) is the main psychoactive cannabinoid in cannabis. It primarily acts on CB1 receptors in the brain, which can alter perception, mood, and cognition.
In Switzerland, hemp products are generally permitted if the THC content is less than 1%. If you are looking for an alternative without psychotropic effects, see our guide on CBD.
01THC: What are we talking about?
THC is one of over 100 phytocannabinoids produced by cannabis. Unlike CBD, it is psychoactive: it can lead to euphoria, altered perception of time and senses, and affect short-term working memory.
02How THC acts in the body
THC preferentially binds to CB1 receptors (central nervous system), modulating neurotransmitter release. It also interacts with CB2 (immunity, peripheral tissues). Effects vary depending on the dose, route of administration (inhalation, ingestion), individual profile, and environment.
03Desired effects and risks
- Desired effects: euphoria, relaxation, sensory alteration, appetite stimulation.
- Possible undesirable effects: anxiety, tachycardia, dry mouth, memory and attention problems, impaired coordination.
- In at-risk profiles: anxious decompensation, possible psychotic syndrome. Tolerance and problematic use possible in some profiles.
Effects vary greatly from one individual to another. For relaxation or sleep aid without psychotropic effects, CBD remains the best-documented alternative.
THC potency has significantly increased, and so has the risk
A synthesis published in 2025 in the Canadian Medical Association Journal notes that the THC content of legal cannabis has increased by approximately 5 times in two decades (from around 4% in the 2000s to over 20% today in some legal markets). The risk of psychosis is significantly higher in people who consume more than 10% THC frequently, who are young or male, especially if they have a history of mental disorders.
This is one of the arguments explaining why Switzerland legally caps THC at 1% in over-the-counter products: a level significantly lower than the thresholds associated with this increased risk in scientific literature.
Detailed sources at the end of the article.04Regulated therapeutic uses
THC, often combined with CBD (nabiximols), is being studied in medicine for spasticity related to multiple sclerosis. A 2024 randomized trial confirms a measurable effect on clinical measures of spasticity. Other regulated uses include chemotherapy-induced nausea. These indications fall within specific medical frameworks, distinct from recreational use.
05Legality in Switzerland and Europe
In Switzerland, hemp products are generally lawful if the THC content is less than 1% in the final product. Products with higher THC levels fall under specific frameworks (local regulations, medical uses, pilot projects). In the EU, many countries align with 0.3% THC for industrial hemp.
06Safety and precautions
- Driving and machinery: to be avoided due to impaired reflexes.
- Pregnancy and breastfeeding: not recommended.
- Adolescents: increased vulnerability of the developing brain.
- Psychiatric or anxious history: increased caution, non-psychoactive alternatives to be preferred.
07Frequently asked questions
What's the difference between THC and CBD?
THC is psychoactive and can alter perception. CBD is not psychoactive and is sought after for stress, sleep, and comfort without getting "high".
Can you drive after taking THC?
No. THC impairs reflexes and coordination.
What alternatives are there if I don't want a psychoactive effect?
CBD, in the form of oils, low-THC flowers, or capsules, remains the most documented option.
08Go further
Cannabinoid guides
Our collections
Blog articles
Cited scientific sources
- Li S, Solmi M, Myran DT, Fabiano N. The potency of cannabis is increasing. CMAJ, 197(27), 2025. Read the study
- Bethoux FA, Farrell R, Checketts D, et al. A randomized, double-blind, placebo-controlled trial to evaluate the effect of nabiximols oromucosal spray on clinical measures of spasticity in patients with multiple sclerosis. Multiple Sclerosis and Related Disorders, 2024. Read the study
This article contains general information for educational purposes and is not a substitute for advice from a healthcare professional.