Possibly - which is why you'll find recommended session frequency and length both here and in Bathmate's official material. Some users who have ignored guidelines report small red dot bruises, uncomfortable swelling, numbness, or general pain and discomfort as a result of overpumping. It's unlikely that overpumping once or twice as you get used to your Bathmate will cause any lasting problems - but continuing to pump if you experience any unpleasant side effects could be more damaging. Use your pump as recommended, and be sure to take breaks if you experience any pain or discomfort.