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Accidentally taking one dose of aspirin when breastfeeding

It is surprising how often mums manage to take products containing aspirin by mistake – they are given by well meaning partners, friends at the office or just taken quickly for pain. Then the realisation that aspirin is contra indicated in breastfeeding. What to do? How long to express?

The answer is actually simple with one single accidental exposure. The risk is low and I have been unable to find any references associating Reye’s syndrome with the amount of aspirin passing through breastmilk.

Reye’s syndrome This is a rare syndrome, characterised by acute encephalopathy and fatty degeneration of the liver, usually after a viral illness or chickenpox. The incidence is falling but sporadic cases are still reported. It was often associated with the use of aspirin during the prodromal illness. Few cases occur in white children under 1 year although it is more common in black infants in this age group. Many children retrospectively examined show an underlying inborn error of metabolism.

accidental/one off dose of aspirin factsheet

Aspirin is not generally recommended to be used by lactating women due to the link between aspirin and Reye’s syndrome. Aspirin is 80–90% bound to plasma proteins. Erickson and Oppenheim (1979) found that even at a dose of 4 g per day the levels of salicylate measured in one mother suffering from rheumatoid arthritis were below the level of detection. Findlay et al. (1981) studied two mothers exposed to 454 mg aspirin. They found that salicylic acid penetrated poorly into milk, with peak levels of only 1.12–1.60 µg per millilitre, and estimated that about 0.1% of the mothers’ total dose would appear in breastmilk.

Accidental consumption of a single dose of aspirin by a lactating mother need not lead to expressing and discarding of her breastmilk. Theoretical infant dose through breastmilk is quoted as 0.25 mg per kilogramme per day with a relative infant dose quoted as 2.5–10.8% (Hale 2017 online access).

The BNF states: ‘Avoid – possible risk of Reye’s syndrome; regular use of high doses could impair platelet function and produce hypoprothrombinaemia in infant if neonatal vitamin K stores low’. Vitamin K is secreted in breastmilk and is added to formula.

If taken accidentally no evidence that continuing to breastfeed after single dose is harmful.


Erickson SH, Oppenheim GL, Aspirin in breastmilk, J Fam Pract, 1979;8(1):189–90.

Findlay JW, DeAngelis RL, Kearney MF, Welch RM, Findlay J, Analgesic drugs in breastmilk and plasma, Clin Pharmacol Ther, 1981;29:625–33.

Glasgow JF, Reye’s syndrome: the case for a causal link with aspirin, Drug Saf, 2006;29(12): 1111–21.

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