I know starting prozac (fluoxetine) can raise anxiety levels initially. my question is, how long does the increase of anxiety when starting prozac (fluoxetine) last?

It varies.: Prozac (fluoxetine) actually is used for treating Anxiety also. If you are feeling more Anxious , and is interfering with your daily routine, you should talk to your doctor. I usually recommend about a week to get adjusted to a new medicine. I believe you must be taking it for Depression. Try Meditation and Relaxation Technique to help with Anxiety