I have two friends who were recently diagnosed with depression. They were both prescribed Prozac by their respective doctors. Both of them are heavy marijuana users and both failed to mention that to their doctors. One has been on Prozac for two months and the other for six weeks. I have noticed that their behavior has become strange: mood swings, paranoia, oversleeping, fatigue. They continue taking their Prozac (20 mg a day) and continue smoking pot. I am afraid that there might be some negative interaction between the substances, one being an antidepressant and the other a depressant. Can you provide some insight?

Recently, my boyfriend began injecting cocaine. I've noticed that he and his friends share their needles, but "clean" them first with bleach and water. Is this a valid way to avoid contamination?

My friend recently smoked some pot laced with cocaine. First of all, is this possible? Whatever the case may be, he seems to be infatuated with the idea of trying straight coke. I've heard that trying coke for the first time is quite dangerous, true? Also, what are the effects of the high? And how detrimental is coke in general?

I was really drunk and don't remember the night clearly, but I think I may have had sex. Now I don't know if I could be pregnant or not. I had never had sex before this. Help me please!

Could you possibly tell me the interactive effects of Zoloft (the anti-depressant) and MDMA (Ecstasy)?

1) I am wondering about the direct effects nitrous oxide has on the brain, and if it is a fallacy that it kills brain cells.

2) What are the health dangers of inhaling nitrous oxide? I have heard people say that it "kills brain cells," but no one seems to know how, to what extent, and what the resulting effects are. Since nitrous oxide is commonly administered as anesthesia, is there a safe way to consume it for recreational use? If the user controls her oxygen intake, do the harmful effects (if any) still occur?

I have a friend at school who quit smoking last year in January, and went back to it in October. I have no idea why, and he also started doing other drugs, such as smoking blunts, doing ecstasy, and taking steroids. The drug that I am worried about him doing the most is ecstasy, because it's a dangerous drug. Also, he is always talking about doing drugs. How can I help him? I still want him to be my friend. Please help. This is serious.