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Duloxetine Side Effects: A Complete Guide

Kristin Hall

Reviewed by Kristin Hall, FNP

Written by Geoffrey C. Whittaker

Published 07/22/2020

Updated 08/05/2023

Let’s talk antidepressants for a second. While movies and TV have mocked or misrepresented depression and the medications that treat it, the reality is, there’s basically no reason to apply stigma to either one — they’re both incredibly common.

According to the National Institute of Mental Health, about 21 million U.S. adults have depression. And for many of these people, one of the most effective ways to stop feeling depressed is to take depression medications like duloxetine for some relief.

Here’s the thing: Prescription medications often come with side effects. You hear them rattled off at the end of a commercial and roll your eyes, wondering, Are the benefits really worth the risks?

That’s ultimately up to you to decide. We’re just here to provide information to help you make that decision, including the common side effects, more serious side effects, interactions and other risks associated with duloxetine.

Let’s get into it.

Common Duloxetine Side Effects

Before we jump into the side effects, it’s important to know what duloxetine is — because it’s not like most antidepressants on the market today. 

Duloxetine is what’s known as a serotonin-norepinephrine reuptake inhibitor, or SNRI. These drugs work primarily on two chemicals in the brain: serotonin and norepinephrine. By increasing the amounts of both, it can improve mood and pain conditions. 

Duloxetine (often sold under the brand name Cymbalta) is used for the treatment of several conditions, including: 

  • Major depressive disorder (MDD)

  • Generalized anxiety disorder (GAD)

  • Diabetic neuropathy (nerve pain)

  • Fibromyalgia

  • Chronic musculoskeletal pain 

That’s an impressive resume. But even if it’s the best treatment for a number of conditions, duloxetine still may not be the “right” treatment for people who struggle with the side effects.

So what side effects should you be worried about? According to the U.S. Food and Drug Administration (FDA), the most common side effects include:

  • Nausea

  • Sleepiness or tiredness

  • Dry mouth

  • Fatigue and drowsiness

  • Constipation

  • Decreased appetite 

  • Excessive sweating

  • Weight loss or weight gain

  • Eye pain

  • Bleeding problems

  • Sexual dysfunction, including anorgasmia and (for men) ejaculation issues

Serious Duloxetine Side Effects

If you experience abnormal or serious side effects when switching your medication to duloxetine or while taking it, contact your healthcare provider for proper medical advice right away. While some effects might be temporary or minor, the serious stuff can create a world of problems.

Possible side effects of duloxetine that could be very serious include:

  • Serious liver problems and skin yellowing

  • Hyponatremia (sudden low sodium levels)

  • A particular form of glaucoma called angle-closure glaucoma

  • Allergic reactions, including skin reactions and trouble breathing

  • Increased risk of suicide

One of the most serious is an increase in suicidal thoughts. The FDA issues a black box warning for duloxetine for this very reason. 

In the early phases of treatment, you may experience worsening depression, including suicidal thoughts or tendencies. Don’t ignore these feelings. Contact your healthcare provider immediately if your depression symptoms seem to be getting worse. 

Duloxetine Interactions and Risks

There are several additional risks associated with duloxetine use, including:

  • Drug interactions

  • Withdrawal or discontinuation symptoms

  • Serotonin syndrome 

  • Other dangers

You’ll want to go through these at least once before taking duloxetine. This can help you prevent some new-user problems, and it may also help you avoid life-threatening medical conditions.

Duloxetine Drug Interactions

Duloxetine may negatively interact with other drugs, so tell your healthcare provider about any and all medications you currently take — prescription, over-the-counter and even nutritional supplements — before you get a prescription for duloxetine online.

Some drugs that don’t “play well” with duloxetine include:

  • Selective serotonin reuptake inhibitors (SSRIs) like paroxetine and fluoxetine

  • Monoamine oxidase inhibitors (MAOIs), including phenelzine

  • Blood thinners

  • Non-steroidal anti-inflammatory drugs (NSAIDs), such as naproxen and ibuprofen 

  • Diuretics

  • Fentanyl

  • St. John’s wort

  • Medications for high blood pressure

  • Ciprofloxacin

  • Linezolid

  • Methylene blue

  • Selegiline

  • Warfarin

Serotonin Syndrome

We also have to touch on the “What happens if I take too much duloxetine?” question. 

Duloxetine can increase your chances of suffering from serious adverse effects, including a potentially lethal condition called serotonin syndrome. 

Serotonin syndrome is basically an overdose of serotonin, which can lead to serious symptoms and potentially death. Luckily, avoiding this is relatively easy — take the prescribed amount of medication only, and simply wait until the next dose if you forget to take it within a short window of your normal time each day.

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Withdrawal Effects of Duloxetine

While you won’t experience an addiction-like withdrawal from discontinuing duloxetine, you could experience withdrawal-type effects if you’ve taken Cymbalta for a long time before suddenly stopping.

Symptoms include increased suicidal thoughts, returning depression symptoms and trouble sleeping, among others.

For these reasons, when you stop taking duloxetine, you need to taper down your medication under the guidance of your healthcare provider. 

Other Effects and Precautions

There are several other things to keep in mind before taking duloxetine. You shouldn’t take duloxetine without talking to your healthcare provider if you have:

  • Bipolar disorder. Duloxetine is not a safe or effective treatment for bipolar disorder, so if you’ve been diagnosed with this mental health condition, consider alternatives with your healthcare provider.

  • Liver disease. If you have liver disease, make sure to share this with the healthcare provider prescribing the medication, as it can affect your liver health.

  • Pregnant or breastfeeding. Women who are pregnant or breastfeeding should talk to a healthcare professional about using this medication. It can pass through the womb as well as transfer through breast milk.

  • Drink or consume certain foods. There are also certain foods to avoid when taking Cymbalta — and that’s not including alcohol, which can be a big no-no. If you’re concerned by the food list or drinking risks, talk to a healthcare provider for support and guidance.

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Understanding Duloxetine Side Effects

Side effects may or may not be a hurdle for you — that’s going to depend on your particular reaction to this medication. But if you’re not sure what to do next — whether duloxetine is going to help or harm — here’s what you need to know:

  • Living with depression or chronic pain can be miserable. Duloxetine, along with many other prescription medications, may help. 

  • Just because side effects are possible doesn’t make them likely. And even in cases where you experience side effects, they’re often preferable to the symptoms you’re trying to treat.

  • Your healthcare provider can help you determine if the potential risks are worth the proven benefits — and help get you on the road to brighter days.

  • If you decide to go off of duloxetine, talk with your healthcare provider about how best to do this. The medication can cause withdrawal symptoms if you stop suddenly, so they may want to slowly wean you off your dosage to minimize these effects.

Still have questions? Want help finding the right treatment for depression or anxiety? We can assist.

Our guides include more detailed looks at the benefits of Cymbalta for depression and Cymbalta for anxiety. We also offer virtual mental health services, including online psychiatry and online therapy.

7 Sources

Hims & Hers has strict sourcing guidelines to ensure our content is accurate and current. We rely on peer-reviewed studies, academic research institutions, and medical associations. We strive to use primary sources and refrain from using tertiary references.

  1. Kang, S. G., Park, Y. M., Lee, H. J., & Yoon, B. (2011). Duloxetine-induced liver injury in patients with major depressive disorder. Psychiatry investigation, 8(3), 269–271. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182394/.
  2. HIGHLIGHTS OF PRESCRIBING INFORMATION: CYMBALTA (duloxetine delayed-release capsules), for oral use. (n.d.-c). https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/021427s053lbl.pdf.
  3. U.S. National Library of Medicine. (n.d.-f). Serotonin syndrome: Medlineplus medical encyclopedia. MedlinePlus. https://medlineplus.gov/ency/article/007272.htm.
  4. Delong C, Preuss CV. Black Box Warning. [Updated 2023 Feb 11]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK538521/.
  5. Dhaliwal JS, Spurling BC, Molla M. Duloxetine. [Updated 2023 May 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549806/.
  6. Sansone, R. A., & Sansone, L. A. (2014). Serotonin norepinephrine reuptake inhibitors: a pharmacological comparison. Innovations in clinical neuroscience, 11(3-4), 37–42. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4008300/.
  7. U.S. Department of Health and Human Services. (n.d.). Major depression. National Institute of Mental Health. https://www.nimh.nih.gov/health/statistics/major-depression.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.

Kristin Hall, FNP

Kristin Hall is a board-certified Family Nurse Practitioner with decades of experience in clinical practice and leadership. 

She has an extensive background in Family Medicine as both a front-line healthcare provider and clinical leader through her work as a primary care provider, retail health clinician and as Principal Investigator with the NIH

Certified through the American Nurses Credentialing Center, she brings her expertise in Family Medicine into your home by helping people improve their health and actively participate in their own healthcare. 

Kristin is a St. Louis native and earned her master’s degree in Nursing from St. Louis University, and is also a member of the American Academy of Nurse Practitioners. You can find Kristin on LinkedIn for more information.

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