Viibryd for Fibromyalgia and Chronic Fatigue Syndrome

Illustration of receptors on a synapse.
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Antidepressants are the most commonly prescribed drugs for people with fibromyalgia or chronic fatigue syndrome, but this class of drugs has a relatively high risk of side effects and the list of possible side effects is long.

A drug called Viibryd (vilazodone) promises to provide relief with fewer adverse effects, and clinical studies suggest that it's significantly less likely to cause weight gain and sexual dysfunction—two side effects that often lead people to go off of other antidepressants.

How Is Viibryd Different?

Viibryd is a type of antidepressant called an SSRI (selective serotonin reuptake inhibitor). But Viibryd is different because it targets more than reuptake.

Reuptake is basically a housekeeping function of the brain. When one neuron (brain cell) sends a message to another, it does so with chemicals called neurotransmitters, and serotonin is a very important one to us, as we typically don't have enough or don't use it properly.

When you have low serotonin (or any neurotransmitter), a message sent using it doesn't have enough power to get from one neuron to the next. It's like a tennis serve that's too weak to get the ball across the net.

The ball boy who runs out to collect these unreceived balls is doing the job of reuptake—getting rid of the used serotonin so it's not cluttering things up. Drugs that slow reuptake keep that ball boy (actually glial cells and presynaptic neurons) from snatching away the neurotransmitter and giving it more time to deliver its message.

So far, we've only looked at one side of the tennis court. What about the guy across the net, the neuron who's receiving the message? That cell has receptors, and each receptor is designed to only receive messages from certain neurotransmitters.

Basically, the receptor is locked, and only the right chemical keys can open it. Viibryd targets certain serotonin receptors with simulated keys and tricks them into the opening, making it easier for the messages to flow from cell to cell.

What we're seeing is that as drugs become more specialized in this way, they continue to be effective with fewer side effects. By zeroing in on specific and limited ways that the brain functions, they can better target the underlying problem instead of changing the function of larger areas of the brain that control things we don't want to mess with.


So far, Viibryd hasn't been studied at all for fibromyalgia or chronic fatigue syndrome. Studies, including some large ones, suggest Viibryd is effective against major depressive disorder, which is common in people with fibromyalgia and chronic fatigue syndrome. Studies also suggest that it's well tolerated. Research published in 2017 found no effect on sexual function in healthy adults.

Side Effects

While Viibryd appears to have fewer side effects than other drugs in its class, that doesn't mean it's side-effect free. (No drug is.) In trials, common side effects included:

  • Diarrhea
  • Nausea
  • Dizziness
  • Insomnia
  • Nightmares/abnormal dreams
  • Vomiting

If you're considering Viibryd, be sure to talk to your doctor and pharmacist about the possible risk and benefits. Your doctor and pharmacist can help you identify potential negative interactions with other medications and supplements you're taking.

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  1. Mayo Clinic. Selective Serotonin Reuptake Inhibitors (SSRIs).

  2. Clayton AH, Durgam S, Li D, et al. Effects of vilazodone on sexual functioning in healthy adults: results from a randomized, double-blind, placebo-controlled, and active-controlled studyInt Clin Psychopharmacol. 2017;32(1):27-35. doi:10.1097/YIC.0000000000000145

  3. Mayo Clinic. Vilazodone; Oral Route.

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