Ill-advised, yes, but is mixing my MAOI with a cough suppressant too risky?
February 27, 2012 7:24 PM   Subscribe

PharmacologyFilter: Realistically, can I take a small dose of dextromethorphan (cough suppressant) with my MAOI and not risk serotonin syndrome?

That's really all there is to my question. I take 450 mg of moclobemide daily. Every time I get a cold I develop a cough that drives me insane. This is the case right now. I desperately want a cough suppressant, but I know that mixing dextromethorphan with SSRIs or MAOIs can cause serotonin syndrome. I used to take dextromethorphan with my SSRI, not knowing that this was dangerous. Can I do the same with my MAOI or is it just too risky? If I just take half a dose? A third? I'm asking here because I know what the answer will be if I ask the pharmacist.

*I've been prescribed codeine in the past, but it doesn't work.
posted by kitcat to Health & Fitness (17 answers total) 2 users marked this as a favorite
DXM with an MAOI can kill you. It regularly kills people. It is not even in the same ballpark as DXM with an SSRI. Don't do it.
posted by Jairus at 7:30 PM on February 27, 2012 [2 favorites]

Like, it's don't-even-take-them-within-two-weeks-of-each-other risky. It is like mixing ammonia and bleach because you can't get a stain out. I cannot overstate this.
posted by Jairus at 7:34 PM on February 27, 2012 [2 favorites]

Response by poster: Jairus, thank you for scaring the silly out of me.
posted by kitcat at 7:47 PM on February 27, 2012 [1 favorite]

Don't do it. Here's a similar-ish AskMe that outlines a number of other remedies you can try.
posted by treehorn+bunny at 7:48 PM on February 27, 2012

Dont fuck with this it's not worth the risk, and also, cough suppressants do not work. There is basically no evidence that they do, so why bother?
posted by latkes at 8:03 PM on February 27, 2012

Hey, thanks for posting this, because of you and Jairus I realized that I need to talk to my doctor about taking Maxalt and Zoloft together. Like, now.
posted by Made of Star Stuff at 8:04 PM on February 27, 2012

I know what the answer will be if I ask the pharmacist.

For future reference, their answer is almost always going to be right. Just because they aren't an M.D. doesn't mean they're not very well versed in the drugs they work with every day.

I definitely hear where you're coming from with the terrible coughing. Warm salt water gargles, staying very hydrated, hot steamy showers, and a neti pot are all going to be your friends. Truth be told, I've found DXM plus mucus just leads to delaying a far worse bout of coughing anyway, so you'd be doing yourself no favors even if it were safe. When you have mucus, you have to get rid of that to get rid of the cough.
posted by Saydur at 8:18 PM on February 27, 2012

Thank you for posting this; I didn't know about this.
And I assume you mean the pharmacist would be unrealistically cautious, but I have found that if you are talking to a pharmacist in person they are usually able to give a clear sense of degrees of risk.
posted by LobsterMitten at 8:36 PM on February 27, 2012

There are other excellent cough suppressants. For me, tessalon (bezonatate) worked well. I have no idea if your drugs interact with it (a skim says no) so ask your doc or pharmacist. In the US it's a prescription drug and kind of old-school.
posted by zippy at 8:56 PM on February 27, 2012 [1 favorite]

Moclobemide lowers the rate of metabolism of dextromethorphan. This problem would be negligible if you planned on taking only one dose, but with subsequent doses, the blood levels of dextromethorphan could rise beyond safe levels. You'd realize something was off pretty quickly once you hit ~2.5 mg/kg and started dissociating.

This isn't on the scale of serotonin syndrome or a tyramine hypertensive crisis in terms of danger, but it's still something to be avoided.
posted by dephlogisticated at 9:01 PM on February 27, 2012

Response by poster: If not seratonin syndrome or a tyramine thing, what is this reaction called?
posted by kitcat at 9:05 PM on February 27, 2012

I think what dephlogisticated is describing is basically DXM overdose--your body can't clear it as fast on an MAOI, so you start to experience the high-dose effects (including hallucinations, dissociation, etc.)
posted by kagredon at 9:20 PM on February 27, 2012

I retract my previous statement. Although moclobemide does inhibit an enzyme responsible for metabolizing DXM, it seems that DXM also has some significant SERT inhibiting properties. This could indeed result in serotonin syndrome. So for multiple reasons, avoid mixing the two drugs.
posted by dephlogisticated at 9:26 PM on February 27, 2012

Is your cough from postnasal drip? If so, you could try a neti pot with warm salt water. Give your doctor a call and ask if there's any other medications you can try for your cough.
posted by IndigoRain at 3:07 AM on February 28, 2012 [1 favorite]

I remember reading not long ago that a study comparing the efficacy of DXM vs. plain honey for cough symptoms in children showed that honey actually worked better. Here is an abstract. I don't know if it's been studied in adults, but I found it to be effective against incessant coughs when I was pregnant and trying to avoid meds.
posted by Jemstar at 7:28 AM on February 28, 2012

It's called "poison". You can read about MAOI's on wikipedia of course, but here's my layman's understanding:

Your liver does this thing call MonoAmine Oxidation, which deactivates poisons. These are poisons we don't call poisons because we all have MAO going on which breaks up these materials. MAOI's inhibit this reaction, meaning these poisons are no longer deactivated and they are free to kill you. As noted above, some MAOIs can keep this process disabled for up to two weeks after you stop taking the drug.

Do not play fast and loose with MAOIs. You can die.
posted by chairface at 10:06 AM on February 28, 2012

Virtually any chemical you can name is toxic to the body in large enough concentrations. As they say, the dose makes the poison.

MAO catalyzes a specific reaction—the oxidative deamination of monoamines. It performs this action on both endogenous monoamines (e.g., serotonin, norepinephrine, dopamine) and trace amines found in the diet (tyramine, tryptamine, etc). None of these chemicals are poisons in the common sense of the word. Tyramine only becomes dangerous when it builds to high concentrations in the blood, which generally only occurs during MAOI therapy.

As an analogy, individuals with phenylketonuria can't metabolize phenylalanine properly, which causes it to build up in the body to toxic levels. But phenylalanine is a common amino acid—one would not call it a poison. It's only toxic in the specific, abnormal conditions of phenylketonuria. Likewise, tyrosine is not specifically a poison, just a common metabolic intermediary that must be maintained (like all endogenous chemicals) at certain manageable levels.
posted by dephlogisticated at 1:19 PM on February 28, 2012

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