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Cymbalta Side Effects & Withdrawal Symptoms

Nausea, headache and a dry mouth are among the most common side effects of Cymbalta. In rare cases, patients have suffered serious — and sometimes fatal — side effects, including liver damage, abnormal bleeding, and suicidal thoughts and behaviors. Suddenly stopping the drug may lead to severe withdrawal symptoms, such as electric shock sensations known as brain zaps.

Last Modified: March 18, 2021
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Cymbalta, a serotonin-norepinephrine reuptake inhibitor (SNRI), is used to treat depression, anxiety, fibromyalgia, chronic musculoskeletal pain and pain related to nerve damage from diabetes.

The most common side effects of the drug include nausea, headache, dry mouth and sleepiness — but more serious side effects may occur.

Like most antidepressants, Cymbalta (duloxetine) may trigger suicidal thoughts and behavior in children, adolescents and adults under the age of 24. As a result, patients should be closely monitored for changes in mood and behavior and the emergence of such symptoms.

People who stop using the antidepressant have also reported debilitating withdrawal symptoms, including electric shock sensations, extreme mood swings, and physical and neurological problems. Other serious side effects — ranging from birth defects to liver toxicity to a dangerous rise in serotonin levels — have also been reported.

Common Side Effects: Nausea, Headache and Dry Mouth

A quarter of patients reported experiencing nausea while taking Cymbalta in clinical trials, making it the most common side effect of the drug. Headache was reported by 16 percent of users and dry mouth developed in 14 percent of 4,843 patients who took the drug. One in nine patients reported drowsiness.

The most common side effects of Cymbalta include:
  • Nausea
  • Headache
  • Dry Mouth
  • Fatigue and weakness
  • Insomnia
  • Dizziness
  • Sleepiness
  • Constipation
  • Diarrhea
  • Decreased Appetite (includes anorexia)
  • Increased Sweating

According to the U.S. National Library of Medicine, other common side effects include changes in urination, vomiting, heartburn and stomach pain. Patients may also experience muscle pain or cramps, changes in sexual desire or ability, and uncontrollable shaking of a part of the body.

Sometimes these symptoms may go away as the body adjusts to the medication. Nausea, for instance, often resolves within a week or two.

But it’s important to contact your doctor if you are experiencing any troubling symptoms. He or she may have suggestions for how to reduce symptoms, or may decide to switch you to a different medication.

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Brain Zaps and Other Withdrawal Symptoms

Quitting Cymbalta abruptly may bring on severe withdrawal symptoms that can last for weeks or even months. To avoid such symptoms, the drug’s manufacturer recommends gradually reducing dosage when stopping the drug.

Did You Know?
A 2005 analysis of clinical trial data by researchers at the Lilly Research Centre found that 44.3 percent of patients who quit using duloxetine experienced withdrawal symptoms versus 22.9 percent in the placebo group.

Symptoms of this phenomenon, known as Cymbalta Discontinuation Syndrome, include severe nausea, dizziness, and electric shock-like sensations in the head called “brain zaps” or “brain shivers.” Some patients who reported symptoms became so sick they were unable to go to work and some need to be treated in a hospital.

Other reported Cymbalta withdrawal symptoms include:
  • Nightmares
  • Headache
  • Fatigue
  • Vomiting
  • Insomnia
  • Anxiety
  • Vertigo
  • Irritability
  • Tingling or prickling sensations of the skin

Withdrawal symptoms appear to be more common with Cymbalta than with other antidepressants. An analysis by the Institute for Safe Medication Practices described 888 reports of withdrawal events for Cymbalta in 2016. That was the largest number for any antidepressant affecting serotonin receptors.

The study noted that drugs with a short half-life — the time it takes for the body to eliminate half of a dose of the drug — generated more frequent and severe side effects. Cymbalta has a very short half-life of about 12 hours.

“Clinical discontinuation studies of antidepressants with shorter half-lives showed 46%-78% of patients experienced two or more symptoms,” according to the analysis.

“Clinical discontinuation studies of antidepressants with shorter half-lives showed 46%-78% of patients experienced two or more symptoms.”

The drug’s maker, Eli Lilly, reported in 2016 that it had reached a framework to settle 140 Cymbalta lawsuits involving 1,470 people who claimed the drug caused severe withdrawal symptoms.

Gradually Tapering Recommended

The drug’s label suggests patients gradually wean off the medication if they decide to stop treatment — but even a taper doesn’t guarantee a symptom-free withdrawal.

“If the decision has been made to discontinue treatment, medication should be tapered, as rapidly as is feasible, but with recognition that discontinuation can be associated with certain symptoms,” the label reads.

It goes on to tell doctors to consider putting patients back on Cymbalta if they have symptoms, and “continue decreasing the dose but at a more gradual rate.”

Somatic Clinical Psychologist Andrew Bingham explains the withdrawal symptoms associated with antidepressants.

However, some patients still reported severe symptoms even when being weaned off the drug.

In court documents, a Kentucky man named Christopher Huff says he attempted to slowly taper off Cymbalta in March of 2014 after taking the drug for seven years.

Despite tapering, he experienced ringing in his ears, suicidal thoughts, stomach discomfort, a fear of going out in public, waves of anxiety, “visual flashes of light which made him panic and strange feelings in the back of his head.”

Serious Side Effects and Warnings

Cymbalta users have also suffered serious, and at times, fatal side effects. The drug may cause seizures or convulsions, manic episodes, changes in blood pressure and falls.

It can be life-threatening when used simultaneously with other central nervous system stimulants. Other serious side infects include liver damage, skin reactions, eye problems, abnormal bleeding and a potentially fatal condition called serotonin syndrome.


Chemicals from Cymbalta may cause liver damage. In some cases, this has been fatal. Symptoms may include itching, right upper abdominal pain, dark urine, yellow skin or eyes, enlarged liver and increased liver enzymes.

Liver damage and Cymbalta pills
Cymbalta may cause enlarged liver and increased liver enzymes.

In October 2005, the FDA extended its warnings for the drug, saying it should not be prescribed to heavy drinkers or people with chronic liver disease. The agency said postmarketing reports of cases of hepatitis and cholestatic jaundice indicated that patients with prior liver problems may have an increased risk of further damage if they take duloxetine.

Severe Skin Reactions

Cymbalta may cause serious skin reactions, including Stevens-Johnson Syndrome, a serious skin and mucous membrane disorder. These reactions could require hospitalization and may be life-threatening. Users may need to stop the drug as a result. Skin blisters, peeling rash, sores in the mouth, hives or any other allergic reactions may indicate a serious skin reaction.

Skin reactions can be a side effect of any antidepressant. A 2014 study in the journal Advances in Dermatology and Allergology said that the conditions can range from mild, drug-induced rash to “dangerous and life-threatening generalized systematic reactions.”

Serotonin Syndrome

In 2017, the FDA required a change to Cymbalta’s warning label to include information on serotonin syndrome.

Serotonin syndrome is a potentially fatal condition that occurs when high levels of the chemical serotonin accumulate in the body. People who take Cymbalta should avoid taking other drugs that increase serotonin levels.

Symptoms of this condition include agitation, hallucinations, coma or other changes to mental status. Coordination problems, muscle twitching, racing heartbeat, or high or low blood pressure are also signs of this syndrome.

Drug Interactions ‘Important Factor’ in Developing Serotonin Syndrome

A 2008 article in the journal Canadian Family Physician reported drug interactions were an “important factor” in people developing the condition. Drug interactions between Cymbalta and other drugs a patient takes can lead to serotonin syndrome and may occur shortly after a patient starts taking the drug.

“Serotonin syndrome is increasingly common but not well recognized by physicians,” study author Dr. Christopher Frank wrote. Increased awareness and monitoring of patients may decrease the risks of serotonin syndrome and other complications, he said.

Eye Problems

Some Cymbalta users are at an increased risk of mydriasis, or dilation of the pupil. The drug is not suitable for patients with uncontrolled narrow-angle glaucoma. The medicine can cause eye pain, changes in vision and swelling or redness in or around the eye.

Antidepressants in general can cause narrow-angle (also called acute-closure) glaucoma, a condition that is considered an ophthalmic emergency and can lead to blindness if left untreated. A 2015 case study by three University of Florida researchers described a patient who developed acute-angle glaucoma (ACG) just two days after starting Cymbalta. She required a procedure called laser iridotomy, which involves cutting a hole in each eye to drain fluid and correct the problem.

“Because the SNRIs, including duloxetine, and SSRIs are commonly used in the management of depression or chronic pain, caution is warranted with the use of these drugs in patients with risk factors for ACG,” the researchers wrote in the journal Annals of Pharmacotherapy.

Abnormal Bleeding

Duloxetine may increase the risk of bleeding or bruising. The risk is greater if a patient takes aspirin, a nonsteroidal anti-inflammatory drug such as ibuprofen or naproxen, or the blood thinner warfarin (Coumadin, Jantoven).

By 2007, the FDA had received 170 unique postmarketing reports of bleeding among patients taking the drug. It called for “abnormal bleeding” warnings to be added to SSRI and SNRI labels. The label warns that bleeding reports have ranged from simple bruising to “life-threatening hemorrhages.”

“Patients should be cautioned about the risk of bleeding associated with the concomitant use of Cymbalta and NSAIDs, aspirin, or other drugs that affect coagulation,” the drug’s label warns.

Low Blood Pressure and Loss of Consciousness

In 2014, the FDA required that a warning of orthostatic hypotension and the risk of falls be added to the drug’s label. Orthostatic hypotension is a sudden drop in blood pressure when a person stands up. It can cause a temporary loss of consciousness called syncope, and patients can suffer injuries from subsequent falls.

According to the drug’s warning label, syncope and orthostatic hypotension “tend to occur within the first week of therapy but can occur at any time during Cymbalta treatment, particularly after dose increases.”

Black Box Warning for Suicide Risk

Cymbalta carries a black box warning stating that antidepressants increased the risk of suicidal thoughts and behavior in children, adolescents and young adults in short-term studies. A black box warning is the FDA’s strongest warning, and the agency requires manufacturers to include this warning in the labeling information for all selective serotonin reuptake inhibitor (SSRI) and SNRI medications.

“In patients of all ages who are started on antidepressant therapy, monitor closely for worsening, and for emergence of suicidal thoughts and behaviors.”

Some patients also reported that discontinuing the drug has led to developing suicidal thoughts. During clinical trials, a 19-year-old patient who was being weaned off the drug killed herself in an Eli Lilly laboratory, The Associated Press reported. Nearly 20 percent of the remaining participants dropped out of the trial within a month.

New users should be aware of these dangers when they receive prescriptions for Cymbalta.

“In patients of all ages who are started on antidepressant therapy, monitor closely for worsening, and for emergence of suicidal thoughts and behaviors,” the drug’s label reads.

Pregnancy and Breastfeeding Risks

Women taking Cymbalta for depression, stress urinary incontinence (SUI) or other conditions should be aware of potential dangers of taking the drug while pregnant. Adverse effects have occurred in testing of pregnant animals, and the risk cannot be ruled out in humans.

A 2013 analysis of data from the Lilly Safety System database identified 90 abnormal outcomes in 233 pregnancies with “known pregnancy outcomes.”

These outcomes included 41 spontaneous abortions, 25 post/perinatal conditions and 19 premature births. But Dr. Sharon L. Hoog and other authors of the study concluded that these rates were consistent with abnormalities in the general population. It’s important to note that Eli Lilly conducted the study, and the authors recognized limitations of the data.

Regardless, you should to talk to your doctor if you are pregnant or may become pregnant during Cymbalta use. Breastfeeding while using the drug is not recommended.

Please seek the advice of a medical professional before making health care decisions.
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