Norman Allan
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M.G. writes, "Currently I am taking Prozac. I would like to switch to St. Johnswort, but I have heard that St. Johnswort is a MAO Inhibitor. While I don't really know what that term means, I was told that if I take St. Johnswort and need to take some over the counter medicine such as Nyquil, it would kill me. The label on Nyquil supposedly says not to take with an MAO Inhibitor. What is your advice on this?

Thank you for any help you can give me."

I guess I should put all the disclaimers in the world in here in case you take St Johnswort and Nyquil and drop dead on us... so, bearing in mind that, as Doctor Duckworth says, "anything can cause anything"... here is my two cents worth...

St. Johnswort, as a herbal, is composed of dozens or even hundreds of active ingredients, and they work ensemble, together... This is why herbals tend to act in a balanced and (with mild herbs like Hypericum) gentle manner. Now, while there is a suspicion that some of these many ingredient might act as a MAOI - mono amine oxidase inhibitors - [ adrenaline is (one of many) mono amines - MAOIs block its degradation. Therefore if you are on MAOIs, like Parnate and some other heavy antidepressants, it can be dangerous, for instance, to eat foods containing the amino acid, Tyrosine (the precursor of adrenaline), foods such as cheese, red wine).

However!!! in practice, St. Johnswort, as a herbal, does not act 9to any great extent) like an MAOI - there is just this scary suspicion that maybe it might, but in practice it does not. I would not myself fear cross reactions with Tyrosine. (I would not however take it, or anything else, with an MAOI like Parnate etc.)

No one knows for sure whether there is any active MAOI like behaviour in St, Johnswort. If you are scared, don't take it, but I, as far as I know, do not think that there is any great potential for harm.

As for St. Johnswort and Nyquil, again, I do not think that there is any great potential for harm, but can you find a safer drug as a substitute for Nyquil?