I trust the pill I am on now. The first one I tried was not for me (lots of side effects).
As with pretty much every birth control there is a slight risk of getting pregnant. You have to decide how much of a risk you are willing to take. Personally I don't use condoms with my b/f. I don't like them and they don't help my odds in not getting pregnant by enough to be substantial.
As long as your g/f can be responsible in taking the pill I think you two should be just fine without a condom. No it's not 100% effective but then again neither is using every method of birth control at once.
Also, I don't think anti-depressants have been listed in the drugs that may interact with with b/c pills. Not all anti- depressants interact with all pills but it is something that should be looked up if it applies to anyone.
If your g/f doesn't think she can take her pill every day (it sounds easier than it actually is) the patch is a new option.
I have to agree with Dilbert1234567 in that abstinence is not even 100% effective. Out of the things I have experienced, read, or heard about.... the only "b/c" that seems 100% effective these days is being gay
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Again, sorry for the long wordy posts tonight (or I guess this morning). I'm going on night 3 with no sleep...sleep deprivation is the devil!