What kind of painkillers? Are you saying the painkillers are Valium and Xanax, because if you are, those are anti-anxiety meds, not really painkillers...although they can relieve muscle tension pain.
You can certainly take Lexapro with Valium or Xanax...a lot of people take that combination. If you need pain medication other than over-the-counter meds like Advil, I'd be careful to take them with Valium or Xanax until you know how your body will react...don't drive or do anything requiring your full attention.
Sometimes I have to take both Xanax and Vicodin, but I'm usually in bed with a huge migraine, and I know I couldn't drive. Hope that helps.