Is it safe to take Cymbalta (duloxetine) while breastfeeding?

Cymbalta (Duloxetine) and Breastfeeding

Duloxetine can be used during breastfeeding with careful infant monitoring, as it transfers into breast milk at very low levels (less than 1% of the maternal weight-adjusted dose), though there are reports of sedation, poor feeding, and poor weight gain in exposed infants. 1

Key Safety Data

Infant Exposure Through Breast Milk:

• Duloxetine is present in human milk with peak concentrations occurring at a median of 3 hours after the maternal dose 1
• The estimated daily infant dose is approximately 2 mcg/kg/day, representing less than 1% of the maternal dose 1
• In a study of 6 lactating women taking 40 mg twice daily, the amount of duloxetine in breast milk was approximately 7 mcg/day 1
• Research confirms infant exposure through breast milk is less than 1% of the maternal weight-adjusted dose, suggesting duloxetine can be safely administered to breastfeeding women 2

Required Infant Monitoring

Critical Warning Signs to Watch For:

• Sedation - monitor for excessive sleepiness or decreased alertness 1
• Poor feeding - watch for difficulty with breastfeeding or reduced intake 1
• Poor weight gain - track growth parameters closely 1

The FDA label explicitly states that infants exposed to duloxetine through breast milk should be monitored for these three specific adverse effects 1.

Clinical Decision Framework

When Duloxetine is Indicated:

• Continue the medication at the therapeutic dose that is effective for the mother 1
• Do not reduce the dose solely due to breastfeeding concerns, as undertreated maternal depression poses significant risks to the mother-infant dyad 3
• Establish baseline infant behavior patterns before starting or continuing duloxetine to detect any changes 4

Risk-Benefit Considerations:

• The developmental and health benefits of breastfeeding should be weighed against the mother's clinical need for duloxetine and potential adverse effects on the infant 1
• Untreated maternal depression carries substantial documented risks including impaired mother-infant bonding, decreased breastfeeding initiation, and harm to infant development 3, 5

Alternative Considerations

If Starting New Antidepressant Treatment:

• Sertraline should be considered first-line therapy for breastfeeding mothers due to minimal excretion in breast milk and low infant-to-maternal plasma concentration ratios 3
• Paroxetine and sertraline are the most commonly prescribed antidepressants during breastfeeding with established safety profiles 3, 5

However, if the mother was already taking duloxetine during pregnancy:

• Continuing duloxetine during breastfeeding is reasonable, as switching medications introduces new risks and the infant may have already been exposed in utero 5
• One case report documented a healthy infant exposed to duloxetine during the second half of pregnancy and the first 32 days of breastfeeding with no observed developmental toxicity 6

Important Caveats

Limitations of Available Data:

• Long-term neurodevelopmental outcomes in infants exposed to duloxetine through breast milk have not been studied 6
• The possibility of functional or neurobehavioral deficits appearing later in life cannot be excluded 6
• Published human experience with duloxetine in lactation remains limited compared to SSRIs like sertraline 2

Practical Management:

• Educate mothers on the specific warning signs (sedation, poor feeding, poor weight gain) that require immediate medical attention 1
• Schedule early follow-up visits after hospital discharge to assess infant well-being 3
• Document infant weight and developmental milestones at each visit 4

Common Pitfall to Avoid:

• Do not advise discontinuation of breastfeeding solely due to duloxetine use, as the benefits of breastfeeding for both mother and infant are well-documented and the drug exposure is minimal 5, 2