What are the side effects of Cymbalta (Duloxetine)?

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From the Guidelines

Cymbalta (duloxetine) commonly causes side effects including nausea, dry mouth, constipation, decreased appetite, fatigue, drowsiness, increased sweating, and dizziness, and more serious side effects such as liver problems, serotonin syndrome, and severe skin reactions can occur, as reported in the most recent study 1.

Common Side Effects

  • Nausea
  • Dry mouth
  • Constipation
  • Decreased appetite
  • Fatigue
  • Drowsiness
  • Increased sweating
  • Dizziness These side effects typically improve within a few weeks as the body adjusts to the medication.

Serious Side Effects

  • Liver problems (yellowing of skin/eyes, dark urine, abdominal pain)
  • Serotonin syndrome (agitation, hallucinations, rapid heartbeat, fever, muscle stiffness)
  • Vision changes
  • Unusual bleeding
  • Severe skin reactions These side effects require medical attention and can be life-threatening if not treated promptly.

Other Considerations

  • Sexual dysfunction, including decreased libido and difficulty achieving orgasm, can occur with Cymbalta use 1.
  • Withdrawal symptoms, such as dizziness, nausea, headache, and irritability, can occur if the medication is stopped abruptly, so tapering is recommended under medical supervision.
  • Blood pressure increases may occur, particularly in patients with hypertension.
  • Weight changes, typically modest weight loss initially followed by potential weight gain with long-term use, can also occur.

It is essential to discuss the potential side effects and benefits of Cymbalta with a healthcare provider before starting treatment, and to closely monitor for any adverse effects, especially during the initial weeks of treatment 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 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

From the Research

Side Effects of Cymbalta (Duloxetine)

The side effects of Cymbalta (Duloxetine) can be categorized into several groups, including:

  • Common side effects:
    • Nausea 3, 4, 5, 6
    • Dry mouth 3, 4, 5
    • Dizziness 3, 4, 6
    • Constipation 3, 4, 6
    • Diarrhea 3, 4, 6
    • Fatigue or somnolence 3, 4
    • Hypertension 3, 7, 6
  • Less common side effects:
    • Dysosmia (distorted sense of smell) 5
    • Dysgeusia (distorted sense of taste) 5
    • Bleeding gums 4
    • Tachycardia (rapid heart rate) 7, 6
    • Sympathomimetic toxicity (a condition caused by excessive stimulation of the sympathetic nervous system) 7
    • Serotonin toxicity (a condition caused by excessive levels of serotonin in the body) 7
  • Rare side effects:
    • Seizures 7
    • Coma (in cases of overdose) 7
    • Arrhythmias (abnormal heart rhythms) 7

Overdose Effects

In cases of duloxetine overdose, the most common effects are sympathomimetic and serotonin toxicity, which can cause symptoms such as tachycardia, hypertension, and nausea 7. However, these effects are typically not severe and do not require intensive care admission.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Serotonin and Norepinephrine Reuptake Inhibitors.

Handbook of experimental pharmacology, 2019

Research

Bleeding gums: duloxetine may be the cause.

Journal of postgraduate medicine, 2007

Research

Duloxetine in military posttraumatic stress disorder.

Psychopharmacology bulletin, 2010

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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