I think it might differ from person to person. My friend's just finished a 6 week course of it. The only side effects were feeling pretty tired afterwards, and now she has a burning sensation in her breast. Her specialist has told her that she may have to live with this, but the sensation could weaken over time. She had to go once a week, over the 6 week period. Not sure how long each session lasted for, but I don't think it was for very long. Hope this helps a bit.