Due to the strong nature of Salvia, you have to be extra careful when taking it while using any other kind of drug, legal or not. Like most drugs, interactions between Salvia and other drugs can cause effects to multiply, and Salvia’s strong effects can have some unpleasant consequences.
Most likely, daily prescription & over the counter medications don’t interact noticeably with Salvia, and the plant can be smoked safely while one is taking these. However, as each drug is unique, there are certain ones that will interact and cause problems, so if you’re taking any medication at the time of Salvia ingesting, those interactions should be well researched. In addition, remember that a friend or other Salvia user not having a problem while on another drug does NOT mean you won’t run into something bad; each person is unique, and effects are unpredictable in that way.
Well-educated and cautious are the two things you should be when ever having to combine other psychoactive drugs with Salvia. If the interaction effects aren’t known, start with a test (small) dose, feeling your way up to a normal Salvia high. Smoke small bits with care and in intervals, and at each interval, if you feel clear-headed and up to the next level, smoke more after a period of time. Never let your guard down, and always have someone with you when starting a new combination or trying a significantly larger dose. If something unexpected happens, that extra sober hand will save you things you can’t imagine.
One person has said that immediately after ingesting a large amount of GABA, he took a hit of Salvia leaf and his lung capacity dropped significantly, causing difficult and “constricted” breathing. It apparently lasted some minutes, and though no similar experiences with Salvia and GABA are widely known, the incident shows that there may be problems with the mix of the two.