Cannabis Use: What To Do
The health effects and risks of marijuana, including smoked, vaped and edible products.
Last revised
Cannabis is legal for adults in many states, but it can still cause dependence, impaired driving and harm to young people and pregnancies.
Key takeaways
- Cannabis use disorder: about 3 in 10 people who use marijuana have it
- Higher risk: people who start using before age 18 or use it daily
- Most useful single change: Wait for an edible to take effect before taking more.
- Commonest mistake: Driving after using cannabis.
- See a doctor if any of the signs under "When to get help" below apply to you.
Do
- Wait for an edible to take effect before taking more
- Store all cannabis products locked up and out of children's reach
- Talk to your doctor if you find it hard to cut down
- Call Poison Control at 1-800-222-1222 if a child or pet eats a cannabis product
Do not
- Driving after using cannabis
- Using it with alcohol or other drugs
- Using it during pregnancy or while breastfeeding
The figures behind the list
Each item above follows from these, published in the guidance named at the foot of the page.
| Measure | Figure |
|---|---|
| Cannabis use disorder | about 3 in 10 people who use marijuana have it |
| Higher risk | people who start using before age 18 or use it daily |
| Edibles | can take 30 minutes to 2 hours to take effect, which raises the risk of taking too much |
| Pregnancy | no amount is known to be safe during pregnancy or breastfeeding |
| Driving | marijuana slows reaction time and impairs coordination |
Related topics
- Vaping and Teens: What the Evidence Actually Says (Teen Health)
- What the Guidance Really Says About Medicines and Driving (Medicines Safety)
- The Evidence on Diabetes and Driving, Without the Hype (Diabetes)
- What the Guidance Really Says About Supplements and the Liver (Liver Health)
Where to go next
- Your Questions About Cannabis Use, Answered
- Cannabis Use in Five Minutes
- Cannabis Use — the reference entry
- Substance Use: The Complete Guide
- What the Guidance Really Says About Vaping and E-Cigarettes
- What the Guidance Really Says About Stimulant Use
When to get help
Call 911 if someone has chest pain, severe anxiety or confusion, trouble breathing or is unresponsive after using cannabis, or if a child is very sleepy after eating an edible. See your doctor for repeated severe vomiting linked to regular use.
Where this comes from
- CDC — Cannabis and Public Health
- National Institute on Drug Abuse — Cannabis (Marijuana)
How this page was put together
Every figure, recommendation and warning above is taken from the guidance named in Where this comes from. Nothing on this page is inferred, summarized or generalized beyond what those bodies publish: where they give a number, it is their number, and where they are silent, so are we. Pages are rebuilt whenever the underlying record changes. Sign-off by a named clinician, where it has happened, is shown at the top of the page along with the date.
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to your doctor, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 911.