Breastfeeding While on Blood Thinners or Anticoagulants

Breastfeeding While on Blood Thinners or Anticoagulants

Blood thinners, also known as anticoagulants are a requirement for some breastfeeding mothers due to a variety of reasons. They are most commonly used as thromboprophylaxis during pregnancy where they are also required postnatally in high-risk groups. I will take a look to see the most commonly used blood thinners to see whether they are safe to use while breastfeeding your baby.

So can you breastfeed while also taking blood thinners or anticoagulants.? Blood thinners or anticoagulants are safe to take while breastfeeding along with close consultation with your doctor. Examples such as warfarin, heparin, and enoxaparin are frequently prescribed to breastfeeding mothers. However, some precautions need to be taken with some anticoagulants. This includes the drug aspirin. This drug has been linked to Reye’s syndrome in children who had a viral infection. 

Is it safe to take Enoxaparin (Lovenox, Clexane) while breastfeeding?

Enoxaparin is more widely known by the brand name Lovenox or Clexane. There is a very low chance that an infant will receive any clinically significant amounts while breastfeeding. Hale mentions in Hales Medication’s and Mothers’ Milk (2019) that the molecular size alone would prevent its entry into breastmilk at levels clinically relevant. He further mentions any that may be present in breastmilk would not be absorbed by the infant due to its poor bioavailability. He, therefore, classes enoxaparin at L2. This means Lovenox and Clexane is probably compatible with breastfeeding due to a limited number of studies carried out in nursing mothers.

According to, there was a study of 10 women where some had received 20 mg and others had received 40 mg during the prepartum and postpartum period. The women had breastfed their babies postpartum. It was found that no bleeding had been detected in the infants while their mothers were receiving enoxaparin therapy. 

Can you take warfarin while breastfeeding?

Warfarin is most commonly used for those at a high risk of developing blood clots. This includes many nursing moms who required warfarin during their pregnancy, and for a short while postpartum. But is warfarin safe to take as a blood thinner or anticoagulant while breastfeeding.? Hale in Medications and Mothers’ Milk (2016) states that warfarin is highly protein bound (99%) in the maternal circulation and therefore very little is secreted into human milk. Lactmed also mentions that no adverse reactions in breastfed infants have been reported from maternal warfarin use during lactation. This includes doses of up to 25 mg daily for up to 7 days. The literature clearly states that warfarin is safe to take while breastfeeding. Warfarin is also one of the oldest blood thinners on the market where no concerns have been raised regarding its usage in breastfeeding mothers and their babies.

Can you breastfeed while taking Heparin

Many women often need to take heparin while they are pregnant such as those with a high risk of getting deep vein thrombosis. This course of treatment usually continues into the postpartum period. This brings us to the question “Can you breastfeed while on heparin”.

Heparin is given as an injection either just under the skin or intravenously. According to the NHS, (UK) heparin as a blood thinner is considered safe and compatible for a nursing mom. There is a low likelihood that it will transfer into the breastmilk in clinically significant amounts. Heparin has a large molecular weight which means that there is a very small chance it will be absorbed through a baby’s gastrointestinal tract. Any heparin that may pass from the milk is also most likely to be destroyed by the gastric contents of the infant. 

Can I take aspirin while breastfeeding?

High dose aspirin is not recommended for use in breastfeeding mothers. According to Lactmed Reye’s syndrome has been associated with aspirin administration in infants with viral infections. The risk of acquiring Reye’s syndrome from the presence of aspirin in breastmilk is unknown. Using an alternative medication would be preferred. states that the World Health Organization Working Group on Human Lactation along with the National Reye’s Syndrome Foundation considers aspirin intake by nursing mothers as unsafe.

Another question nursing moms may ask is “Can I take baby aspirin while breastfeeding”. Baby aspirin contains a low dose of 81mg used as a preventative measure of having a stroke or heart attack. As far as we can see just one study has been carried out at this dose on breastfeeding mothers. Results showed that acetylsalicylic acid (aspirin) levels were below the limit of quantification in all the milk samples. It concluded that the daily use of an 81 mg dose of aspirin should be considered during lactation.

Aspirin has also been used for many years as a painkiller. However, Dr. Hale advises that ibuprofen (Advil, NeoProfen), or acetaminophen (Tylenol) should be used as an alternative for pain relief in breastfeeding mothers. 

Could Blood thinners or Anticoagulants affect your Breast Milk Supply

Is has been shown that some medications and even some herbs can have an effect on a mother’s milk supply. However, there are no studies to say whether blood thinners could have a negative effect on milk supply. 

Each decision to breastfeed whilst also taking any of these anticoagulants should always be taken along with the close consultation of your doctor. The use of anticoagulants or blood thinners while breastfeeding will depend on individual assessment and made on the basis of individual risk: benefit analysis. Speak with your doctor immediately if you experience any untoward side effects.


Hale’s Medications & Mothers’ Milk (2019), Thomas W.Hale, Springer Publishing Company, 11 West 42nd Street, New York, NY 10036

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