Can you take acid (LSD) while on prescribed medications?

Of course you "can" -- nothing is stopping you.  The real question is should you.  It depends a lot on which prescribed medications you're on, but to be safe you shouldn't.  If your prescribed medications are for some mental condition, such as depression, anxiety, or schizophrenia, you absolutely should >> not << take LSD.

And then there is the question, how do you know that what you've got is really LSD?  Since it is still illegal, all you know is what the person who sells it to you says.  The synthesis of LSD is long and difficult, and it requires a fully equipped organic lab, so the chances of getting genuine, pure LSD on the street are very small indeed.

You might get more answers by moving this question to Medicine, since it isn't really a question about Chemistry.

I've taken LSD several times, never while on any medication but there are many conditions that would make taking LSD a very bad idea