Antidepressants like duloxetine (Cymbalta) help millions of people alleviate their symptoms of depression, anxiety, and other health conditions every year.
Like other prescription medications approved by the U.S. Food and Drug Administration, Cymbalta can cause side effects.
The most common side effects with Cymbalta include nausea, dizziness, fatigue, and dry mouth.
Another side effect that worries some patients before taking this medication is weight gain.
But does it really cause patients to gain weight?
In this article, I’ll describe how Cymbalta works, its possible side effects, and whether or not the medication can cause weight gain.
Before starting Cymbalta or another antidepressant, talk to your doctor about your medical history and other medications you’re currently using to ensure you are taking the best medication for your needs.
What is Cymbalta?
Cymbalta is a type of antidepressant medication called a serotonin and norepinephrine reuptake inhibitor, or SNRIs.
Serotonin and norepinephrine are chemicals called neurotransmitters.
These chemicals carry messages for your nervous system between your brain and body.
Both norepinephrine and serotonin can also regulate mood.
Normally, when neurotransmitters finish relaying their messages, they’re reabsorbed by the brain, a process called “reuptake.”
SNRIs work by blocking the reabsorption of serotonin and norepinephrine in the brain.
This increases the amount of these chemicals in the brain, which can affect mood, stress, digestion, and pain perception.
Cymbalta can be prescribed to treat:
- Major depressive disorder (MDD)
- Generalized anxiety disorder (GAD)
- Chronic pain, including fibromyalgia, arthritis, and diabetic neuropathy
If you’re prescribed Cymbalta, take the medication only as directed by your doctor.
Don’t take a different dose than what was prescribed, and don’t take it for a longer or shorter period of time than recommended by your doctor.
After starting Cymbalta, it can take 2-8 weeks for the medication to start taking effect.
Though some mild side effects can occur during that period, many can resolve on their own. If any side effects persist, reach out to your doctor.
Does Cymbalta Cause Weight Changes?
Some people have reported weight changes, most notably weight gain, when taking antidepressant medications like Cymbalta.
Overall, the research evidence for weight gain related to Cymbalta is mixed, but does not show big swings in weight in either direction.
One study of Cymbalta’s treatment of major depressive disorder (MDD) in more than 1,000 people found that the medication can actually decrease appetite, eventually leading to weight loss for some patients.
In analyses of 10 clinical studies, researchers found that after short-term treatment with Cymbalta, patients lost, on average, about one pound.
Treatment that lasted up until one year coincided with weight gains of around two pounds.
Overall, the evidence suggests that Cymbalta has minimal effects on weight for the majority of patients.
Do Other Antidepressants Cause Weight Gain?
The research is also mixed on how significantly or directly other antidepressants cause weight gain.
One of the biggest limitations in studying this effect is eliminating other possible causes of weight gain, including biological factors like age and genetics, and socioeconomic factors like stress and access to healthy foods.
Still, evidence shows that some antidepressants can cause a minimal to modest weight change in some people.
In a population-based study from the UK, researchers reviewed data from over 300,000 men and women for up to 10 years after starting antidepressant use.
While the study found a risk of increase in weight over this time period, it was also unable to determine whether reported weight gain was a direct result of antidepressant use, or other factors.
Existing research does suggest that some antidepressants are more likely to cause weight gain than others, including:
- Amitriptyline (Elavil)
- Imipramine (Tofranil)
- Nortriptyline (Aventyl)
- Paroxetine (Paxil, Pareva)
- Mirtazapine (Remeron)
Unfortunately, experts aren’t sure what causes antidepressants to affect weight.
Some believe that the medication’s impact on neurotransmitters in the brain have an indirect impact on metabolism, while others suggest that it’s an indirect side effect of the medications’ ability to treat the respective condition (depression, anxiety, etc).
Ultimately, neither weight loss nor weight gain is a guarantee when taking antidepressants.
For most people, the benefits of antidepressant use outweighs the risk of minimal weight changes.
Other Side Effects of Cymbalta
The most common side effects of Cymbalta are mild.
Other less common side effects are also possible when taking the medication:
- Decreased appetite
- Irregular menstrual cycle
- Increased risk of bleeding events
Though rare, there are some more severe risks associated with Cymbalta use in some people:
- Increase in blood pressure
- Liver failure
The side effects of Cymbalta will vary depending on the person, which is why it’s important to consult with your doctor before starting the medication.
Tell your doctor if any new, persistent, or bothersome side effects occur.
When to Talk to a Doctor
When taken as directed, Cymbalta can be a safe and effective treatment option for depression, anxiety, or chronic pain.
However, if the medication isn’t working to resolve your symptoms after several weeks, reach out to your doctor to discuss whether adjusting the dose or switching medications may be helpful.
If you experience any of the rare, but serious, signs of an allergic reaction, tell your doctor right away. These include:
- Severe dizziness
- Hives, or a red or purple rash with blistering or peeling
- Itching or swelling, particularly of the mouth, face, or throat
- Trouble breathing
Additionally, reach out to your doctor immediately if you experience any of the following:
- Panic attacks
- Worsening mood
- Feeling agitated, impulsive, aggressive, restless, or hyperactive
- Thoughts of suicide
If you’re having a mental health emergency, call 911 or go to the nearest emergency room. You can also get free 24/7 support from a suicide and crisis expert by calling or texting 988. If you’d prefer to chat online, you can chat with a suicide and crisis expert by visiting the Lifeline Chat.
How K Health Can Help
Think you might need a prescription for Cymbalta (Duloxetine)?
K Health has clinicians standing by 24/7 to evaluate your symptoms and determine if Cymbalta is right for you.
Get started with our free assessment, which will tell you in minutes if treatment could be a good fit. If yes, we’ll connect you right to a clinician who can prescribe medication and have it shipped right to your door.
Frequently Asked Questions
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.
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Antidepressant utilisation and incidence of weight gain during 10 years’ follow-up: population based cohort study. (2018).
Anxiety Facts and Statistics. (2020).
Duloxetine (Cymbalta). (2020).
Duloxetine in the treatment of major depressive disorder. (2007).
Effects of antidepressant and antipsychotic use on weight gain: A systematic review. (2019).
Effects of the Antidepressant Duloxetine on Body Weight: Analyses of 10 Clinical Studies. (2006).