Is it safe to use ambien (zolpidem) and ativan together?

Maybe: If used at same time, sleep depth and duration will increase, maybe dangerously. People who have developed tolerance to one or both drugs will have less trouble, but may still have trouble. Consult your doctor before combining them.

If prescribed: If your physician prescribed both of these to you, s/he probably told you to take them at different times -- not together. They would be mutually sedating. If these were not prescribed to you -- and you have them from another source instead -- please don't use them at all.