Marijuana/cannabis has been deemed illegal until only very recently and because of this, extensive studies on cannabis have not been conducted. Such as, what are the effects of mixing cannabis and anti-depressants? Now that marijuana is legal, more experiments will be conducted on how it effects our everyday lives and therefore, we will have a clearer idea on the effects of marijuana when mixed with prescription medication.
It is important to remember that marijuana IS a psychoactive drug–it DOES alter the way your brain receives and processes information. Every person reacts differently to different substances; especially when multiple substances are being consumed. If your friend is prescribed Prozac, for example, and smokes weed, they may not experience any adverse effects from the marijuana. For this person, marijuana does not interact with their anti-depressants negatively. However, you or another friend may react differently to the same mixture of drugs. Mixing marijuana and a prescribed anti-depressant can be the reason for a list of unwanted symptoms.
Some studies have shown that smoking marijuana as a teen can lead to an onset of psychosis or even schizophrenia, especially if one has a genetic predisposition to schizophrenia. Cannabis does not cause or create schizophrenia, but it can trigger psychotic symptoms for people already vulnerable to the illness (Scientific American, 2014).
The point is to be weary about using another substance with a prescription medication. This includes any street drug, as well as alcohol, and other pharmaceutical drugs. Just because marijuana is legal now does not mean that it is safe to use in conjunction with other prescription medications.
Continue to watch for new research on this topic!