Septembermorn - I hate to be the bearer of news you don't wanna hear, but there is really no interaction between SSRIs (like Celexa™ - citalopram) and cannabis. The grouchiness and disconnectedness is the pot talking. The cannabis is an escape, plain and simple. That's why people use it. The good news is is that it is fairly non-toxic when compared to other substances used for the same reason (ie. escape from reality). Just be glad it's not cocaine, ecstasy, or even alcohol. Actually, of these 3, alcohol probably the worst. Alcohol's effects seem to be intensified when one is taking an SSRI (and I've never really figured out a mechanism as to why). As for the ecstacy, SSRIs tend to deaden the high. Cocaine in moderation is safe, physiologically speaking (as long as one is young and healthy); the only problem is is that with its short half-life and intense activity in the brains pleasure center (nucleus accubens) it is almost impossible to use in moderation, when used for escaping reality.

In a way you can be glad she's apathetic and lethargic; it will keep her out of trouble (ie. little impulsivity). There is a very rare condition called cannabis psychosis, but chances of that happening are scant. As long as the pot isn't an every day thing and her life doesn't revolve around getting more, to stay doped, there should be little problem. Most people do grow out of using pot; I think that most people just come to realize that not being able to think clearly is rather frustrating. Also, you can only sit like a lump in front of the T.V. so long (well, maybe not a teenager, but you'd expect an adult to get bored with that rather fast).

You can discourage her use of cannabis, just don't be fanatical about it. The more you make a big deal out of it, the more she'll be tempted to keep using it.. She knows that she can get you worked up by smoking it, and it gives her a reason to keep using it (it reminds her of being young and a rebel).

Sorry that I don't have any legitimate ammunition that you can use. Just be glad she's made a relatively non-toxic and benign choice (aside from any legal ramifications). - Cam