Can you take clemastine while breastfeeding?
What LactMed says
The National Library of Medicine’s own summary, quoted in full. We do not write a verdict of our own on this question, and we do not compress theirs into a label.
Small occasional doses of clemastine are acceptable during breastfeeding. Larger doses or more prolonged use may cause drowsiness and other effects in the infant or decrease the milk supply, particularly in combination with a sympathomimetic such as pseudoephedrine or before lactation is well established. Single bedtime doses after the last feeding of the day may be adequate for many women and will minimize any effects of the drug. The nonsedating antihistamines are preferred alternatives.
Quoted from Clemastine — Drugs and Lactation Database (LactMed®), National Institute of Child Health and Human Development, revised February 15, 2026.
What LactMed would consider instead
LactMed ends this record by naming the drugs it would consider in place of clemastine. Whether any of them fits depends on what you are treating — this is the database’s list, not a recommendation from us.
How much clemastine gets into breastmilk
Maternal Levels. The milk clemastine level was 5 to 10 mcg/L 20 hours after the last dose in a 1 mg twice daily regimen in one woman. A simultaneous serum level was 20 mcg/L.
Infant Levels. Relevant published information was not found as of the revision date.
What has been seen in breastfed infants
A 10-week-old breastfed infant whose mother was taking clemastine, phenytoin and carbamazepine was drowsy, refused to feed, was irritable, and had high-pitched crying. These side effects were possibly caused by clemastine in breastmilk, but the other drugs could also have contributed.
In one telephone follow-up study, mothers reported irritability and colicky symptoms 10% of infants exposed to various antihistamines and drowsiness was reported in 1.6% of infants. None of the reactions required medical attention.
Effects on milk supply
Antihistamines in relatively high doses given by injection can decrease basal serum prolactin in nonlactating women and in early postpartum women. However, suckling-induced prolactin secretion is not affected by antihistamine pretreatment of postpartum mothers. Whether lower oral doses of antihistamines have the same effect on serum prolactin or whether the effects on prolactin have any consequences on breastfeeding success have not been studied. The prolactin level in a mother with established lactation may not affect her ability to breastfeed.
Frequently asked questions
Can you take clemastine while breastfeeding?
Small occasional doses of clemastine are acceptable during breastfeeding. The full record is quoted on this page, and the decision is one to make with the person who prescribed it — LactMed itself states it is not a substitute for professional judgement.
What can I take instead of clemastine while breastfeeding?
LactMed lists Cetirizine, Desloratadine, Fexofenadine, Levocetirizine, Loratadine as alternate drugs to consider. That is the database's own list for this drug — whether any of them suits you depends on what you are treating.
Does clemastine pass into breastmilk?
LactMed's measured drug levels for clemastine are quoted in full on this page, under "How much gets into breastmilk".
Do I need to pump and dump after taking clemastine?
LactMed does not frame its records that way — it reports measured drug levels in milk and what has been observed in breastfed infants, which is what this page quotes. "Pump and dump" advice for a specific drug and dose should come from your clinician or a pharmacist, not from a general rule.
More on clemastine
LactMed states that the information it presents is not a substitute for professional judgement, and that you should consult your healthcare provider for breastfeeding advice related to your particular situation. Nothing on this page is medical advice.