What are the side effects of Cymbalta (duloxetine)?

Common Side Effects of Cymbalta (Duloxetine)

Duloxetine (Cymbalta) has numerous common side effects including nausea, dry mouth, sleepiness, fatigue, constipation, loss of appetite, increased sweating, and dizziness, with nausea being the most frequently reported adverse effect. 1

Common Side Effects

Duloxetine commonly causes the following side effects:

• Gastrointestinal effects:

  • Nausea (most common)
  • Dry mouth
  • Constipation
  • Diarrhea
  • Vomiting
  • Abdominal discomfort
  • Decreased appetite and weight loss

• Neurological effects:

  • Dizziness
  • Headache
  • Somnolence/sleepiness
  • Fatigue
  • Insomnia
  • Tremor

• Other common effects:

  • Diaphoresis (increased sweating)
  • Sexual dysfunction
  • Changes in blood pressure (both increases and decreases)

Serious Side Effects

While less common, duloxetine can cause several serious adverse effects that require immediate medical attention:

1. Liver damage - Watch for symptoms such as:

   • Itching
   • Right upper abdominal pain
   • Dark urine
   • Yellow skin or eyes (jaundice)
   • Enlarged liver
   • Increased liver enzymes 1

2. Serotonin syndrome - A potentially life-threatening condition with symptoms including:

   • Agitation, hallucinations, coma
   • Coordination problems or muscle twitching
   • Racing heartbeat
   • High or low blood pressure
   • Sweating or fever
   • Nausea, vomiting, diarrhea
   • Muscle rigidity
   • Seizures 1

3. Severe skin reactions - Including erythema multiforme and Stevens-Johnson syndrome 2, 1

4. Abnormal bleeding - Especially when combined with blood thinners, NSAIDs, or aspirin 1

5. Blood pressure changes and fall risk - Particularly in elderly patients 1

6. Discontinuation syndrome - When stopping the medication abruptly, symptoms may include:

   • Anxiety and irritability
   • Dizziness
   • Electric shock-like sensations
   • Headache
   • Nausea, vomiting, diarrhea
   • Sleep disturbances 1

Special Considerations

• Drug interactions: Duloxetine may interact with medications metabolized by CYP1A2 and CYP2D6 2

• Contraindications: Concomitant use with MAOIs is contraindicated due to increased risk of serotonin syndrome 2

• Pregnancy and breastfeeding: Duloxetine passes into breast milk and may harm babies 1

• Hepatic concerns: Should be discontinued if jaundice or other evidence of clinically significant liver dysfunction develops 2

Monitoring Recommendations

When taking duloxetine, the following should be monitored:

• Blood pressure and pulse
• Weight and appetite
• Mood changes (including suicidal thoughts)
• Liver function (if symptoms of liver problems develop)
• Signs of abnormal bleeding

Dosing Considerations

Starting at a lower dose (30 mg daily) for one week before increasing to 60 mg daily may reduce the risk of treatment-emergent nausea while producing only a temporary impact on effectiveness 3. This approach may be particularly helpful for patients concerned about side effects.

Rare But Reported Side Effects

Some less common but documented side effects include:

• Bleeding gums 4
• Dysosmia (smell disturbances) and dysgeusia (taste disturbances) 5
• Visual problems (eye pain, vision changes, swelling or redness around the eye) 1
• Low sodium levels in the blood (particularly in elderly patients) 1
• Urination problems (decreased urine flow) 1

Remember that while this list of side effects may seem extensive, not all patients experience them, and many side effects are mild and transient. However, any concerning symptoms should be promptly reported to a healthcare provider.