my sister chose the shot. u can only be on it for 2 yrs. it seriously thins out your bones. she didnt gain wt she lost it and she was thin to start. her bones look like that of an 80 yr old in her bone scan. it happens due to lack of periods. she is on the yasmin pill now. the ring can be removed during sex u have to remember to put it back in after. the ring and patch do not go through your liver. these 2 forms start working immediately, unlike the pill which u have to take an entire pack to get the blood levels up to prevent pregnancies. the shot is good for 3 months that will give your girlfriend some time to see if she likes it and she can switch to something else if she prefers. all the forms of hormonal birth control carry risks. the cost and convenience vary also.