Let me preface this by saying that I have no formal medical training, and I am not a doctor or medical professional. While vacuum pumping does carry some risks, when done carefully, it can be done safely. The most frequent problem is someone who is overly anxious to see their penis very large, and goes overboard on the pumping, applying too much pressure to the penis. Applying too much pressure can result in temporary bruising or discoloration of the penis, water blisters, and minor bleeding. Most symptoms usually disappear, in healthy males, after a few days. The important thing to remember is to go slow and increase the vacuum gradually over a longer period of time, so that the change in size is not traumatic and does not cause damage to the penis. It is so safe, in fact, that it is the only non-surgical method approved by the FDA for penis enlargement. Medical Doctors have been using vacuum pumps to treat impotence for years. If done carefully, pumping is safer than surgical alternatives to penis enlargement.