"i have recently gotten of the shot, but i was on it for about a year and a half. i got on it when i was 17, for my periods, and it does indeed live up to its name for stopping periods. however, i gained about thirty five pounds on the shot. i&#039;m very active, and have a proper diet for a girl my age, so it&#039;s likely the hormones. but that&#039;s not the reason i got off it, i started lactating out of my breasts about a month ago. yes, i told my doctor and we took 2 pregnancy tests, and i am not pregnant. so, in short, i&#039;ll give you a quick pros and cons list
pros: prevents pregnancy (i do not use condoms with my partner), stops periods 
cons: weird side effects, mood swings, nausea, constipation, weight gain, breast growth, hair loss, fatigue."