What are the side effects of Duloxetine (Cymbalta)?

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Last updated: April 6, 2025View editorial policy

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From the Guidelines

Cymbalta (duloxetine) can cause several side effects, including common ones like nausea, dry mouth, and dizziness, as well as more serious ones like suicidal thoughts, liver problems, and serotonin syndrome, and patients should be closely monitored for these adverse effects, particularly when starting or stopping treatment 1.

Common Side Effects

  • Nausea
  • Dry mouth
  • Constipation
  • Decreased appetite
  • Fatigue
  • Drowsiness
  • Increased sweating
  • Dizziness These side effects typically appear within the first few weeks of treatment and often improve with time.

Serious Side Effects

  • Suicidal thoughts (particularly in young adults and adolescents)
  • Unusual changes in behavior or mood
  • Liver problems (yellowing of skin/eyes, dark urine, upper abdominal pain)
  • Severe skin reactions
  • Eye pain or swelling
  • Serotonin syndrome (agitation, hallucinations, rapid heart rate, fever, muscle stiffness) Cymbalta can also cause sexual dysfunction, including decreased libido and difficulty achieving orgasm.

Monitoring and Tapering

Blood pressure changes may occur, so regular monitoring is recommended. When stopping Cymbalta, patients should work with their healthcare provider to taper the dose gradually to avoid withdrawal symptoms like dizziness, irritability, headaches, and "brain zaps" 1.

Special Considerations

Duloxetine has been associated with hepatic failure presenting as abdominal pain, hepatomegaly, and elevation of transaminase levels, and should be discontinued and not restarted in patients who develop jaundice or other evidence of clinically significant liver dysfunction 1. Severe skin reactions, including erythema multiforme and Stevens-Johnson syndrome, can occur with duloxetine, and the medication should be discontinued and not restarted at the first appearance of blisters, peeling rash, mucosal erosions, or other signs of hypersensitivity 1.

From the FDA Drug Label

Duloxetine delayed-release capsules may cause serious side effects, including:

  1. liver damage. Symptoms may include: itching right upper abdominal pain dark urine yellow skin or eyes enlarged liver increased liver enzymes
  2. changes in blood pressure and falls. 3 Serotonin Syndrome: This condition can be life-threatening and symptoms may include: agitation, hallucinations, coma or other changes in mental status coordination problems or muscle twitching (overactive reflexes) racing heartbeat, high or low blood pressure sweating or fever nausea, vomiting, or diarrhea muscle rigidity dizziness flushing tremor seizures 4 abnormal bleeding: 5 severe skin reactions: 6 discontinuation symptoms: 7 manic episodes:
  3. visual problems:
  4. seizures or convulsions
  5. low salt (sodium) levels in the blood.
  6. problems with urination The most common side effects of duloxetine delayed-release capsules include:
  • nausea
  • dry mouth
  • sleepiness
  • fatigue
  • constipation
  • loss of appetite
  • increased sweating
  • dizziness

The possible side effects of Cymbalta (duloxetine) include:

  • Serious side effects: liver damage, changes in blood pressure and falls, serotonin syndrome, abnormal bleeding, severe skin reactions, discontinuation symptoms, manic episodes, visual problems, seizures or convulsions, low salt levels in the blood, and problems with urination.
  • Common side effects: nausea, dry mouth, sleepiness, fatigue, constipation, loss of appetite, increased sweating, and dizziness. 2 2 2

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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