Alcohol
Alcohol and cannabis are two of the most commonly used drugs in the US, so it isn’t surprising that some people use them at the same time. However, using alcohol and cannabis together is not recommended because of the way they interact, significantly increasing the risk of adverse health effects than either alone.
Alcohol increases the absorption of THC, adding to the sensation of being high, but also intensifying negative side effects.
Combined use can also affect reaction time and other cognitive functions, increasing the risk of being in a car crash if driving.
Prescription Drugs
Cannabis can interfere with other drugs in various ways. Combining drugs affects the effectiveness of prescription medicines, and neurotoxins may be produced from the interactions. You should always talk with your medical provider and/or pharmacist before using cannabis while taking prescription medicine.
Tobacco, Cannabis, and Secondhand Smoke
Burning any plant material releases toxic chemicals and fine particles that can go deep into the lungs. Cannabis smoke contains many of the same components and toxins as tobacco smoke, some in higher quantities. There are few specific studies on the effects of secondhand cannabis smoke on people; however, a study that exposed rats to secondhand cannabis smoke raised cause for health concerns.
More information on this topic can be found in the “Cannabis and Health” section.