Marijuana (THC)

What is it?
First Aid

What is marijuana?

Marijuana is the dried leaves and flowers of the cannabis plant. It contains the drugs THC (tetrahydrocannabinol) and CBD (cannabidiol), along more than one hundred related chemicals. Other cannabis preparations include hashish and hash oil.

Marijuana users most often smoke the plant product or take it in edible preparations, such as brownies, cookies or candy.

Studies about possible medical benefits of marijuana are ongoing. Currently the FDA has only approved three medications containing marijuana-related chemicals. These are available only by prescription from a doctor for very specific conditions related to certain types of epilepsy, HIV/AIDS and cancer treatment. Maine, New Hampshire and Vermont have each approved medical marijuana programs that allow treatment of a wider range of conditions. However, research is limited on how safe and effective these uses of marijuana are.

Marijuana can be harmful to young children or pets who swallow it unknowingly. Children may be especially drawn to edible products, such as brownies, cookies and candy.

Teens and adults who use marijuana may also experience unwanted symptoms, especially at high doses, such as from taking a second dose of an edible product before effects from the first one have kicked in.

Note: Synthetic marijuana products, such as K2 and Spice, are designed to mimic THC, but their effects can be very different. Learn about these street drugs on our synthetic cannabinoids page.

What are the effects of marijuana?

Typical effects of marijuana and other cannabis preparations include:

  • Sleepiness
  • Dizziness
  • Decreased coordination
  • Slowed reaction time
  • Increased appetite
  • Dry mouth
  • Coughing and lung irritation (from smoking)
  • Euphoria (a high)

Most of these effects continue for hours after the high has ended. The effects on coordination and reaction time make it unsafe to drive while under the influence of marijuana.

Marijuana use can also make the symptoms of depression and anxiety worse. Long-term use can lead to dependence.

What are the symptoms of marijuana poisoning?

Children who accidentally swallow marijuana can become very drowsy. In severe cases you may not be able to wake the child up, and they may have trouble breathing. Children who swallow marijuana often need to be watched at a hospital to ensure their safety.

Teens and adults who use a large amount of marijuana, especially in edible products, may experience unpleasant hallucinations or other intense changes in sensory perception. They may also experience a type of cyclic vomiting syndrome, in which they throw up repeatedly anywhere from several hours to a few days.

Pets can have symptoms similar to those seen in people, including loss of coordination, slowed reaction time and drowsiness.

What should I do if someone has used marijuana?

  • If a child has swallowed marijuana, call the poison center at 1-800-222-1222 for immediate advice. A poison specialist will tell you what to do at home and whether you need to take the child to the hospital. 
  • If a teen or adult isn’t feeling well after using marijuana, get advice from the poison center—1-800-222-1222, chat online or text POISON to 85511.


How can I prevent marijuana poisonings?

  • If you have marijuana in your home, especially edible products, keep it up high, out of reach of children and pets, in a locked cabinet if possible.
  • If you are using edible products, avoid taking more than the recommended dose. Be aware that it usually takes at least 30 minutes to feel effects from edibles, and 2 to 4 hours for the strongest effects.
  • If you or someone you know has a substance use problem, use SAMHSA’s treatment services locator to find help near you.

Last Updated: Wednesday May 16th 2018