Hi, Thanks for posting in HCM. I understand your concern. Pentogen contains medroxyprogesterone. It is active semi-synthetic derivative of progesterone used as long acting contraceptive. Weight gain is a known side effect of the drug. Also intense pains you are getting behind the ribs could also be due to fluid retention as Pentogen also known to cause water retention. Kindly get yourself checked by consulting Physician to exclude water retention and check for any problems with the lungs and cardia. In case these symptoms continue to bother you, you may need to change the mode of contraception which would suit you. Hope the information provided would be helpful. All the best.