If you have depression, an anxiety disorder, or pain caused by certain conditions, your doctor might suggest Cymbalta (duloxetine) as a treatment option. Along with other questions you may have about the drug, you could be wondering about its side effects.

Cymbalta is a prescription drug that’s used as a long-term treatment for several different conditions.

Cymbalta is approved to treat the following conditions in adults:

Cymbalta is also approved to treat these conditions in children:

  • GAD in children ages 7 years and older
  • fibromyalgia in children ages 13 years and older

For more information about Cymbalta, including details about its uses, see this in-depth article.

Like other drugs, Cymbalta can cause mild or serious side effects. Keep reading to learn more.

Some people may experience mild or serious side effects during Cymbalta treatment. Some side effects are more common than others.

Cymbalta’s more common side effects include:

* To learn more about this side effect, see “Side effects explained” below.

Mild side effects have been reported with Cymbalta, many of which are also more common side effects of the drug. Cymbalta’s mild side effects include:

* In this article, we use the terms “female” and “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article. For details on sexual side effects Cymbalta may cause, see “Sexual side effects in women and men” below.
† To learn more about this side effect, see “Side effects explained” below.

In most cases, these side effects should be temporary. Some may be easily managed, too. But if you have any symptoms that are ongoing or that bother you, talk with your doctor or pharmacist. And don’t stop using Cymbalta unless your doctor recommends it.

Cymbalta may cause mild side effects other than the ones listed above. See the Cymbalta medication guide for details.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Cymbalta, visit MedWatch.

Serious side effects from Cymbalta aren’t common, but they can happen. Serious side effects that have been reported with Cymbalta include:

* Cymbalta has a boxed warning for this side effect. This is the most serious warning from the Food and Drug Administration (FDA). To learn more, see “Side effects explained” below.
† To learn more about this side effect, see “Side effects explained” below.
‡ An allergic reaction is possible after using Cymbalta. But this side effect wasn’t reported in studies.

If you develop serious side effects while taking Cymbalta, call your doctor right away. If the side effects seem life threatening or if you think you’re having a medical emergency, immediately call 911 or your local emergency number.

The most common side effects of Cymbalta in children may include:

Sexual side effects from taking Cymbalta are possible and may be more common in males than females.* In studies, sexual side effects were reported in a small percentage of males and females during Cymbalta treatment. Some of these side effects, such as erectile dysfunction, may be more likely to occur when taking a higher dosage of Cymbalta.

Males who took Cymbalta reported significantly more sexual side effects compared with those who took a placebo (a treatment that contains no active drug). The sexual side effects reported in males included:

Females who took Cymbalta also reported sexual side effects. But these side effects were similar to those experienced by females who received a placebo. Sexual side effects included:

Note that some males and females in this study reported improvements in sexual desire, performance, and satisfaction with Cymbalta treatment. This may be because the medication helped to reduce the symptoms of their condition. As a result, their sexual health may have also improved.

* In this article, we use the terms “female” and “male” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Some side effects of Cymbalta can affect your long-term health, but this isn’t common.

For example, liver failure is a rare but serious side effect of Cymbalta. Heavy alcohol use may increase the risk of liver failure. The liver damage that develops from this side effect doesn’t go away once a person stops taking Cymbalta.

You may be wondering if it’s safe to take Cymbalta long term. Studies have tested the drug’s safety for up to 6 months. A 2009 study has shown Cymbalta to be safe to use when taken for 12 months. Your doctor can tell you about their understanding of long-term Cymbalta use.

It’s a good idea to go over all of your medications with your doctor every so often. Together, you can discuss your condition and consider whether you should continue Cymbalta long term.

Keep reading to get answers to some frequently asked questions about Cymbalta’s side effects.

How long do Cymbalta’s side effects last?

How long side effects from Cymbalta last can vary. Some of the more common side effects are usually temporary, such as sleepiness, dizziness, and reduced appetite. These side effects typically ease within a few days or weeks after starting treatment.

Common side effects may get worse after your doctor increases your dosage, but this is usually temporary.

Other side effects are more likely to continue for as long as you’re taking the drug. Examples include sweating more than usual and sexual side effects. These side effects usually aren’t severe.

Cymbalta side effects can affect each person differently. For example, nausea may be a mild, temporary side effect for some people. For others it can be bothersome. In studies, a small percentage of people had to stop taking the drug due to nausea.

If you’re experiencing troublesome side effects, you shouldn’t suddenly stop taking Cymbalta. It’s best to talk with your doctor first. If you and your doctor decide that you should stop the drug, they’ll guide you on how best to do so.

Do seniors have a higher risk for side effects from Cymbalta?

No, this doesn’t seem to be the case. In general, older adults (ages 65 years and older) have a higher risk for medication side effects compared with younger adults. But in studies of Cymbalta, older adults had similar side effects to those of younger adults.

Can Cymbalta cause weight gain?

Cymbalta doesn’t typically cause weight gain. In studies, weight gain wasn’t reported as a side effect.

In fact, weight loss is more likely than weight gain with Cymbalta. This is because the drug commonly causes reduced appetite and nausea.

These side effects may lead to weight loss, especially in children. Because of this, if your child is taking Cymbalta, their doctor will monitor your child’s weight and height during Cymbalta treatment.

If you have questions about weight changes with Cymbalta, talk with your doctor.

Will Cymbalta side effects differ depending on the strength I use (20 mg, 30 mg, or 60 mg)?

Some side effects of Cymbalta may be dependent on dose. Cymbalta comes in the following strengths: 20 milligrams (mg), 30 mg, and 60 mg. A higher strength of the drug might come with a higher risk of certain side effects.

Common dose-dependent side effects of Cymbalta include nausea, fatigue (lack of energy), constipation, dizziness, reduced appetite, and sweating more than usual.

Learn more about some of the side effects Cymbalta may cause.

Sweating more than usual

Sweating more than usual is a common side effect of Cymbalta. This side effect may be worse with higher doses of the drug. In addition, hot flashes (also called hot flushes) are a possible side effect of this medication.

Some people may notice increased sweating only in certain situations, such as when they’re active or during humid weather. Others may have increased sweating more often, including while trying to sleep.

What might help

Increased sweating isn’t a harmful side effect, but it may be uncomfortable. Here are a few tips that may help ease this side effect:

  • Use a strong deodorant.
  • Shower more often.
  • Wear light fabrics
  • Use a fan at night.

If this side effect continues to bother you, your doctor may suggest adjusting your dosage or switching to a different drug.

But if Cymbalta is particularly effective for your condition, you may not want to switch to a different drug. In this case, your doctor may suggest treatments for your sweating. Examples of drugs sometimes used to treat this side effect include:

If you have concerns about sweating more than usual with Cymbalta, talk with your doctor.

Eye problems

Eye problems aren’t a common side effect of Cymbalta. But this drug may increase the risk of serious eye problems, such as glaucoma (a buildup of pressure within the eye).

Cymbalta can cause a person’s pupils to dilate. This can trigger a serious eye problem, including vision loss, especially for someone who has closed-angle glaucoma. Symptoms can include:

  • sudden vision changes
  • eye pain
  • eye redness
  • swelling in or around your eye

What might help

If you have closed-angle glaucoma, you shouldn’t take Cymbalta. If you’re not sure whether you have this condition, consider visiting an eye doctor. The results of an eye exam can help you and your doctor decide if it’s safe for you to take Cymbalta.

If you develop any of the above symptoms while taking Cymbalta, you should seek medical attention. Urgent treatment is needed to help prevent permanent vision loss.

If you have questions about eye problems that Cymbalta may cause, talk with your doctor.

Liver damage

Although rare, Cymbalta can cause serious liver damage that could be fatal. The risk of this side effect may be higher with alcohol use. It could also be higher in people who already had liver problems before starting Cymbalta.

The following may indicate that there’s a problem with your liver:

What might help

To help prevent this side effect, talk with your doctor about any liver problems you’ve had. It’s also important to be honest about your alcohol use. Talk with your doctor about whether you’ve had problems with your liver or alcohol use in the past.

If you develop any of the above symptoms, get emergency medical care right away.

Trouble sleeping

Insomnia (trouble falling asleep or staying asleep) can occur with Cymbalta. In studies, this side effect was more commonly reported in people taking the drug for long-term musculoskeletal pain. (This is pain in the bones, muscles, tendons, ligaments, and nerves.) Waking up earlier than desired was also reported with Cymbalta.

Insomnia is also a common side effect reported in children taking Cymbalta.

What might help

Here are a few tips that may help to improve your sleep:

If you’re having insomnia since starting Cymbalta, talk with your doctor. They may suggest the temporary use of a sleep aid, such as melatonin. Or they may adjust your dosage or discuss other treatment options with you.

Suicidal behaviors and thoughts

Cymbalta has a boxed warning for suicidal behaviors and thoughts. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). It alerts doctors and patients about drug effects that may be dangerous.

Antidepressants such as Cymbalta may increase the risk of suicidal behaviors and thoughts in children and young adults ages 24 years or younger. This is a rare side effect. Studies show that the risk is higher after a person first starts treatment or increases their dose.

What might help

While taking Cymbalta, you should watch for any new behaviors, feelings, or thoughts. This is especially important in the first few weeks after starting Cymbalta or after your dose is adjusted.

Consider using a journal or app to make notes about your mood. You may want to ask your loved ones to let you know if they notice that you’re acting differently. Tell your doctor right away if you or someone else notices any changes in your behavior or moods.

Suicide prevention

If you think someone is at immediate risk of self-harm or hurting another person:

  • Call 911 or your local emergency number.
  • Stay with the person until help arrives.
  • Remove any guns, knives, medications, or other things that may cause harm.
  • Listen, but don’t judge, argue, threaten, or yell.

If you or someone you know is considering suicide, get help from a crisis or suicide prevention hotline. Try the National Suicide Prevention Lifeline at 800-273-8255.

Allergic reaction

Like most drugs, Cymbalta can cause an allergic reaction in some people. But this side effect wasn’t reported in studies.

Symptoms can be mild or serious and can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. To manage symptoms, they may suggest an over-the-counter antihistamine you take by mouth, such as Benadryl (diphenhydramine). Or they may recommend a product you apply to your skin, such as hydrocortisone cream.

If your doctor confirms you had a mild allergic reaction to Cymbalta, they’ll decide if you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you had a serious allergic reaction to Cymbalta, they may have you switch to a different treatment.

Keeping track of side effects

During Cymbalta treatment, consider keeping notes on any side effects you’re having. You can then share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of drug you were taking when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help your doctor learn more about how Cymbalta affects you. Your doctor can use this information to adjust your treatment plan if needed.

Cymbalta has several warnings that may affect whether you can safely use this drug to treat your condition.

Boxed warning: Suicidal behaviors and thoughts

Cymbalta has a boxed warning for suicidal behaviors and thoughts. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Antidepressants such as Cymbalta may increase the risk of suicidal behaviors and thoughts in children and young adults ages 24 years or younger. After starting Cymbalta, you should watch for any new behaviors, feelings, or thoughts. Tell your doctor right away if you or your loved ones notice any changes in your behavior or moods.

To learn more, see “Side effects explained” above.

Other warnings

Cymbalta may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Cymbalta. The list below includes factors to consider.

Liver or kidney problems. The liver and kidneys help clear Cymbalta from the body. In a person who has liver or kidney problems, Cymbalta levels could become too high in their body. This can worsen the drug’s side effects. In rare cases, Cymbalta may cause liver failure. People who already have liver problems may be at higher risk for this side effect. Before taking Cymbalta, tell your doctor about any liver or kidney problems you have.

Closed-angle glaucoma. Cymbalta can cause the pupils to dilate, which may worsen certain eye problems. If you have closed-angle glaucoma, vision loss could occur with Cymbalta. Talk with your doctor about other treatment options.

Heart or blood pressure conditions. Cymbalta may increase your blood pressure. If you already have high blood pressure or heart problems, taking Cymbalta could worsen your condition. Before starting this drug, tell your doctor about any heart or blood pressure problems you may have.

Slow stomach emptying. Cymbalta capsules are delayed-release. As such, they have a special coating that helps protect the drug against the acid in your stomach. If you have a condition that can slow stomach emptying, such as diabetes, the special coating may get destroyed. This could make Cymbalta less effective for treating your condition. Before taking Cymbalta, talk with your doctor about any medical conditions that you have.

Diabetes. If you have diabetes, Cymbalta may make it more difficult to manage your blood sugar levels. Before taking Cymbalta, talk with your doctor about a plan for managing your blood sugar levels.

Seizures. Cymbalta may increase the risk of seizures. But the drug hasn’t been studied in people with epilepsy (a seizure disorder). If you have a seizure disorder, your doctor may suggest another treatment option for your condition.

Bipolar disorder or mania. Cymbalta may bring on or worsen certain symptoms of bipolar disorder or mania. If you have bipolar disorder or mania, talk with your doctor about the risks involved in taking Cymbalta. If you aren’t sure whether you have either condition, your doctor may screen you for them before you take Cymbalta.

Low sodium levels. Cymbalta can cause low sodium levels. If you have problems with your sodium levels, talk with your doctor before you take Cymbalta.

Bleeding problems. Cymbalta may raise your risk for bruising or bleeding problems. If you have a condition that causes bleeding problems, taking this drug may worsen your condition. Before starting Cymbalta, tell your doctor about any current or past bleeding problems.

Allergic reaction. If you’ve had an allergic reaction to Cymbalta or any of its ingredients, you shouldn’t take Cymbalta. Ask your doctor what other medications are better options for you.

Alcohol use and Cymbalta

Drinking alcohol isn’t recommended with Cymbalta, especially heavy alcohol use.

Alcohol may worsen some of Cymbalta’s common side effects, such as:

  • nausea
  • sleepiness
  • dizziness

Heavy alcohol use while taking Cymbalta can increase your risk for serious liver problems and liver failure. This can be life threatening.

If you drink alcohol, talk with your doctor about whether it’s safe for you to do so while taking Cymbalta. You can also ask them how much alcohol is safe for you to drink.

Pregnancy and breastfeeding while taking Cymbalta

Cymbalta use isn’t recommended during pregnancy because its effects aren’t fully known. The drug may cause harm to a developing fetus.

If you’re pregnant or you’re considering a pregnancy, talk with your doctor. They’ll tell you about treatment options that may be safer during this time.

Cymbalta passes into breast milk, and the drug may affect a child who is breastfed. There have been reports of drowsiness and feeding problems in children breastfed by people taking Cymbalta.

If you’re breastfeeding or have plans to breastfeed, talk with your doctor. They can help you weigh the pros and cons of breastfeeding while taking this drug.

Many people find that Cymbalta is an effective treatment for their condition. When you’re considering Cymbalta as a treatment option, it’s a good idea to talk with your doctor about your risk for side effects. Here are some questions that you may want to ask:

  • Do my medical conditions increase my risk for side effects with Cymbalta?
  • Are there other ways to help me manage side effects from Cymbalta?
  • Are there any lifestyle changes I can make that may help to reduce my need to take Cymbalta in the future?

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Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.