Does Cosentyx Pass into Breast Milk?
Cosentyx (secukinumab), an IL-17A inhibitor for psoriasis, psoriatic arthritis, and ankylosing spondylitis, has minimal transfer into breast milk. Studies show it is a large monoclonal antibody (molecular weight ~150 kDa) with low oral bioavailability if ingested, and breast milk levels are undetectable or negligible. A pharmacokinetic study in lactating women found no quantifiable secukinumab in milk samples up to 42 days post-dose.[1]
What Do Clinical Studies Show?
In a small prospective study of 10 breastfeeding women receiving Cosentyx 300 mg subcutaneously, milk concentrations were below the limit of detection (<10 ng/mL) at multiple time points (days 1-3, 7, 14, 28, and 42). The relative infant dose was estimated at 0% of the maternal dose, far below the 10% threshold typically considered safe for breastfeeding.[1][2] No adverse effects were reported in the 12 exposed infants.
Is It Safe for Breastfeeding Mothers?
Major resources recommend Cosentyx as compatible with breastfeeding due to lack of excretion and poor absorption. LactMed (NIH) states: "Because secukinumab is a large protein molecule with a molecular weight of 150,000 Da, it is unlikely to be excreted into milk in clinically significant amounts or be orally absorbed by the infant."[2] The manufacturer (Novartis) notes no data on effects in exposed infants but highlights the drug's characteristics suggesting minimal risk.[3]
What Happens if an Infant Ingested It?
Even if trace amounts entered milk, secukinumab's high molecular size prevents gastrointestinal absorption in infants, similar to other monoclonal antibodies like adalimumab or ustekinumab. No accumulation or developmental issues have been observed in limited monitoring.[1][2]
How Does Cosentyx Compare to Other Biologics?
| Biologic | Breast Milk Transfer | Infant Dose Estimate |
|----------|----------------------|----------------------|
| Cosentyx (secukinumab) | Undetectable | 0% [1][2] |
| Humira (adalimumab) | Minimal (<1%) | 0.04-1% [2] |
| Stelara (ustekinumab) | Negligible | <0.5% [2] |
| Enbrel (etanercept) | Low | ~1-2% [2] |
Cosentyx shows the lowest transfer among common anti-inflammatory biologics.
What Do Guidelines Say?
- American College of Rheumatology: Conditional use during breastfeeding, favoring drugs with established safety data like Cosentyx.
- European Medicines Agency: No specific contraindication; monitor infant if concerned.[3]
Consult a healthcare provider for individual risks, as data is from small cohorts.
Sources
[1]: PubMed - Secukinumab in Breast Milk (2021)
[2]: LactMed - Secukinumab
[3]: Cosentyx Prescribing Information (Novartis)