SSRI + SNRI = synergestic?
February 11, 2018 6:47 AM   Subscribe

If I were to take half a dose of an SNRI (example, Effexor) and half a dose of an SSRI (example, Zoloft), would I be at greater risk of having Serotonin Syndrome than if I were to take the same total dose but of only one drug?

Are their mechanisms of action different, such that they are synergestic (the result of their interaction is more than cumulative), or are they non-synergestic (5mg of Effexor and 5mg of Zoloft results in the same risk of Serotonin Syndrome as 10mg of Effexor or 10mg of Zoloft)?
posted by thesockpuppet to Grab Bag (7 answers total) 1 user marked this as a favorite
 
You psychiatrist should be able to answer that question. I can't see a reason that it would make sense to do that.

As an aside, I would personally be very hesitant to take SNRIs due to the legendary difficulty of getting off them
posted by kbbbo at 7:15 AM on February 11, 2018


As smart as people here are, you should only accept an answer about this from your prescribing doctor.
posted by yes I said yes I will Yes at 7:46 AM on February 11, 2018 [6 favorites]


Data point: I was taken off an SSRI that stopped working to go on an SNRI.

To kbbbo’s point, I haven’t had any of the expected side effects from “side-Effexor”, and have been told that those tend to be predictive of trouble when titrating down. But potential side effects beat current suicidality in my book, if that’s the algebra. Anyway, not directly relevant to serotonin syndrome.
posted by chesty_a_arthur at 8:05 AM on February 11, 2018 [2 favorites]


I can say that I've known people taking far more Effexor than that along with Abilify and some illegal drugs on top without ever ending up with serotonin syndrome. At least for that person, it's apparently quite hard to trigger. There have been a few times I was pretty sure they were intentionally trying to trigger it. :p

Point being that I seriously doubt that you'd be at significant risk taking both together unless they were each near or above the maximum daily recommended dose, especially under the direction of a medical professional.
posted by wierdo at 10:43 AM on February 11, 2018


Oh, and as far as mechanism of action goes, they do essentially the same thing, it's just that their primary effect is on different neurotransmitters. Effexor is called an SNRI because in lowish doses it only has a significant effect on the reuptake of norepinephrine. However, in higher doses it also slows the reuptake of serotonin. Many things called SSRIs similarly will have effects on other neurotransmitters in high doses.

Point being that a low dose of an SSRI that is highly specific to serotonin and a low dose of Effexor should operate on different neurotransmitters. Since low dose Effexor has a very limited effect on serotonin, I wouldn't expect it to be particularly synergistic with low doses of SSRIs. In higher doses, I could see there being a risk.
posted by wierdo at 11:23 AM on February 11, 2018


Response by poster: yes I said yes I will Yes - Psychiatrists are conservative, understandably so because of potential liability, so they go by the book. But my reaction to antidepressants are on the extreme end of normal. For instance, I normally take 7mg of Zoloft alone, which is far below the therapeutic dose but I can't go any higher due to the side effects.

Wierdo - actually, Effexor at low doses affects serotonin and acts as an SSRI, while at higher doses it acts as an SNRI.
posted by thesockpuppet at 12:00 PM on February 11, 2018


If you don't trust your psychiatrist's opinion, then talk to your primary care doctor about it.

I had a physician refuse to prescribe my migraine medicine (triptans) alongside zoloft because of the risk of Serotonin syndrome; I spoke with my PCP about and she said she'd had dozens of patients taking both, and had never once seen a problem.

But serotonin syndrome's no joke, so you MUST talk to a physician about this and ONLY take your medication as directed.
posted by Made of Star Stuff at 2:44 PM on February 11, 2018 [1 favorite]


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