Suppose you don’t have erectile dysfunction, but have an undiagnosed heart problem. Because Viagra works by enlarging blood vessels, it can potentially cause blood pressure to drop. A sudden decrease in blood pressure, as you may know if you ever stood up too quickly, can cause you to faint.
If you take illicit substances along with recreational Viagra, you could be in for an unpredictable experience. That’s because many street drugs cause blood vessels to constrict. It may sound like Viagra would nicely cancel out this effect, but it’s less predictable than that. And if you obtain “Viagra” from sketchy sources, there’s no telling what’s actually in it.
Fake Viagra has been found to contain any number of nasty chemicals, some of which are dangerous on their own, others of which could interact badly with illicit drugs. In other words, you’re taking a big risk with your health for a benefit that might not be worth it.