Cannabis use may affect fertility. Regular or heavy cannabis use has been linked to changes in the female menstrual cycle and lower sperm count, or lower sperm quality in men.
Other risks of regularly using cannabis can include:
Regular cannabis use increases the risk of developing a psychotic illness, such as schizophrenia.
Other risks of cannabis
Read the latest updates on cannabis, cannabinoids and cancer – the evidence so far on the Cancer Research UK website.
Cannabis contains active ingredients called cannabinoids. 2 of these – tetrahydrocannabinol (THC) and cannabidiol (CBD) – are the active ingredients of a prescription drug called Sativex. This is used to relieve the pain of muscle spasms in multiple sclerosis.
Some examples include:
Regularly smoking cannabis with tobacco increases the risk of a baby being born small or premature.
Cannabis contains substances that affect the brain and body, including delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). THC causes the intoxicating effects of cannabis. CBD is not intoxicating but can still have effects on the brain.
There are risks associated with cannabis use. The best way to protect your health is to avoid using cannabis or cannabis products completely.
On this page
If you have questions, visit your health care provider.
Everyone’s response to cannabis can also differ from one time to the next.
Using cannabis frequently (daily or almost daily) and over a long time (several months or years) can:
The potential medicinal properties of marijuana and its components have been the subject of research and heated debate for decades. THC itself has proven medical benefits in particular formulations. The U.S. Food and Drug Administration (FDA) has approved THC-based medications, dronabinol (Marinol ® ) and nabilone (Cesamet ® ), prescribed in pill form for the treatment of nausea in patients undergoing cancer chemotherapy and to stimulate appetite in patients with wasting syndrome due to AIDS.
The FDA also approved a CBD-based liquid medication called Epidiolex ® for the treatment of two forms of severe childhood epilepsy, Dravet syndrome and Lennox-Gastaut syndrome. It’s being delivered to patients in a reliable dosage form and through a reproducible route of delivery to ensure that patients derive the anticipated benefits. CBD does not have the rewarding properties of THC.
Medical Marijuana Laws and Prescription Opioid Use Outcomes
An additional concern with “medical marijuana” is that little is known about the long-term impact of its use by people with health- and/or age-related vulnerabilities—such as older adults or people with cancer, AIDS, cardiovascular disease, multiple sclerosis, or other neurodegenerative diseases. Further research will be needed to determine whether people whose health has been compromised by disease or its treatment (e.g., chemotherapy) are at greater risk for adverse health outcomes from marijuana use.
Researchers generally consider medications like these, which use purified chemicals derived from or based on those in the marijuana plant, to be more promising therapeutically than use of the whole marijuana plant or its crude extracts. Development of drugs from botanicals such as the marijuana plant poses numerous challenges. Botanicals may contain hundreds of unknown, active chemicals, and it can be difficult to develop a product with accurate and consistent doses of these chemicals. Use of marijuana as medicine also poses other problems such as the adverse health effects of smoking and THC-induced cognitive impairment. Nevertheless, a growing number of states have legalized dispensing of marijuana or its extracts to people with a range of medical conditions.
In addition, several other marijuana-based medications have been approved or are undergoing clinical trials. Nabiximols (Sativex ® ), a mouth spray that is currently available in the United Kingdom, Canada, and several European countries for treating the spasticity and neuropathic pain that may accompany multiple sclerosis, combines THC with another chemical found in marijuana called cannabidiol (CBD).