Yes, it can. But I'm guessing it's the Lexapro, because that's one of its more common side effects. Happened to me with it, happens to many who take it. During the time I was on Lexapro I started taking 3 showers a day, and often had to get up and shower so I could go back to sleep. However, the prohibition of 5-HTP does apply when you take an SSRI -- you shouldn't take both. 5-HTP can also cause night sweats in some people, though probably fewer than Lexapro. I am wondering why you would take it after your doc correctly told you not to, but that's another issue. Serotonin syndrome is a much more severe problem than just getting the sweats. I have no idea how one would take a supplement containing serotonin, don't know of such a thing. 5-HTP isn't serotonin, it's a metabolite of L-tryptophan, the amino acid that along with B6 and Vitamin C and other co-factors allows the body to manufacture serotonin. SSRIs like Lexapro use this serotonin to do what they do, which is alter the way the body naturally utilizes it. If you're on an SSRI, you obviously don't want to take anything else that affects serotonin unless your doc tells you to because what you're doing isn't working well enough and therefore takes the risk of someone getting serotonin syndrome, but again, that's not what you're describing. Don't take the HTP again unless you stop taking SSRIs or other drugs that affect serotonin. Peace.