1. Fluvoxamine (Luvox) and caffeine don't mix well.

I'm amazed how many patients are not informed of this.

Disclaimer: I am not an MD, but rather a patient with some experience reading the medical literature.

2. The basic reason is simple: fluvoxamine inhibits the cytochrome P450 enzyme encoded by the CPA1Y2 gene. This enzyme is responsible for "metabolizing" caffeine in the body.

The result is that caffeine lasts much, much longer in your body if you taking Luvox.

3. Caffeine can seem like a wonder drug, but only because its persistence in the body is on the same time scale as our sleep-wake cycle. In most people, it is. The half life of caffeine tends to be on the order of a few hours. What you drink in the morning is mostly gone by bed.

4. Fluvoxamine massively increases the half-life of caffeine in the body. Here's one study, which estimates a mean half-life of 4.9 hours for subjects not on fluvoxamine, and a mean half-life of 56 hours for subjects on fluvoxamine.

bpspubs.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2125.2005.02467.x

5. So if you are on Luvox and drink coffee in the morning, most of that caffeine will still be in your system at bedtime. This can interfere with sleep in a major way, particularly if you're consuming larger doses of caffeine.

6. It can also lead to a vicious cycle. After a bad night's sleep, you drink more coffee because you're tired in the morning. Then that night, you can't sleep because the caffeine is still in your system. So the next morning, bleary eyed, you repeat....

Ask me how I know.

7. In my view this not adequately documented in drug interaction databases, drug information websites, etc.

Here's drugs.com. It notes an possible interaction but doesn't come close to explaining how long caffeine will last in your system.

8. It also seems to get the story backward, at least with respect Culm-Merdek et al. (above).

That study concludes that fluvoxamine affects caffeine pharmacokinetics (here, how long it lasts in the body) but not pharmacodynamics (here, the effects of a given concentration).

9. So if you take fluvoxamine (Luvox), you need to be aware of these effects. Or if you have friends and loved ones who are taking it, let them know.

*Again I'm not an MD let alone a psychiatrist. Just a patient with a PhD in biology and some experience reading the literature.