Cannabis (marijuana) has no known lethal dose or LD5O. This makes cannabis one of the least toxic substances known. Therefore, it has very few drug interactions and low potential to cause combined adverse effects. Although, a few have been reported that should be discussed.
Alcohol effects may be increased when combined with cannabis, increasing risk of dizziness, loss of coordination, nausea and vomiting. Theoretically, cannabis is an anticonvulsant and may suppress vomiting and lead to alcohol poisoning. However, this is not significantly reported
Opiate medications Combined cannabis use does not increase the risk of overdose by opiate medications. In fact, studies are suggesting that cannabis may make opiate medication more effective at managing pain at lower doses
Sedatives can make patients very drowsy. Combining these medications with cannabis may cause excessive sleepiness. Examples: clonazepam (Klonopin), lorazepam (Ativan), phenobarbital (Donnatal), Zolpidem (Ambien)
Disulfiram (Antabuse) manufacturer reports that combined with marijuana may cause irritability and disturbances of sleep
SSRI’s and other mood altering drugs have had a few reports of interactions such as irritability and nervousness. Patients taking these medications should discuss their medical cannabis use with the prescribing physician. Examples: fluoxetine (Prozac) and sertraline (Zoloft)