I have anxiety so my doctor prescribed venlafaxine 37.5mg. After one week my heart rate was above 100 and I felt very drowsy, but now it's fine. Everytime I check my heartbeat it's above 100. Before using this medicine, and even with my anxiety, my heart rate remained at 80 to 85 when I had panic attack. Can anyone tell me if it is normal to experience increased heart rate in the early weeks of using venlafaxine or I should consult my doctor?