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 the long-term, widespread-pain disorder fibromyalgia and chronic fatigue syndrome, characterized by extreme tiredness. However, 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) was created to provide relief with fewer adverse effects. Also, clinical studies suggest that it's significantly less likely to cause weight gain and sexual dysfunction—two side effects that often cause people to go off of other antidepressants.

How Is Viibryd Different?

Viibryd, approved by the Food and Drug Administration in 2011, 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 neurotransmitter. It is, in fact, a key hormone that stabilizes our moods, feelings, and happiness. Sometimes our bodies lack this hormone.

When you have low serotonin levels, or low levels of 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.

Think of the opposing player as 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 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 interfere with.


So far, Viibryd hasn't been studied 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 free from side effects. (No drug is.) In trials, common side effects include:

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

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

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3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  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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