Last update Aug. 22, 2021

C9 H8 O4

Likely Compatibility

Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.

A non-steroidal anti-inflammatory drug (NSAID) with analgesic, anti-inflammatory and antipyretic properties.
Usually administered orally, every 4-6 hours to reduce pain or fever and every 24 hours and at low dose (100 mg/day) as an platelet antiaggregant.
The consumption of aspirin has been quite reliably related to the appearance of Reye syndrome, especially in early childhood (Schrör 2007, Waldman 1982), so in many countries its use is discouraged in children under 12-16 years of age (Unsworth 1987).

It is excreted in small amounts in breastmilk (Datta 2017, Athavale 2013, Bailey 1982, Findlay 1981, Erickson 1979), becoming insignificant when the maternal doses of aspirin are less than 500 mg (Datta 2017).

Although low plasma levels have been detected in infants (Unsworth 1987), there have been no reports of Reye syndrome due to aspirin in breastmilk and it is considered very unlikely that it could occur with isolated doses or at low doses used in antithrombotic treatments and for anti-abortion purposes.

Various medical associations and expert consensus consider safe or probably safe its occasional isolated use or in antiaggregant dose during breastfeeding (Datta 2017, Noviani 2016, Rowe 2013, Sachs 2013, Bates 2012, Bell 2011, Chen 2010, Bar-Oz 2003, WHO 2002, Spigset 2000).

With maternal doses in the usual analgesic - antipyretic - anti-inflammatory therapeutic range there are three old publications on side effects in the infant: a very doubtful case of salicylic poisoning in the neonatal period (Clark 1981), thrombocytopenia in an infant (Terragna 1967) and a hemolytic crisis in a 23-day-old infant affected by glucose-6-phosphate dehydrogenase deficiency (Harley 1962).
Other studies have not found any problem in infants whose mothers were taking aspirin (Ito 1993).

For use at usual doses as an anti-inflammatory, analgesic or antipyretic, safer known alternatives are preferred during breastfeeding (Noviani 2016, Davanzo 2014, Bloor 2013, Sachs 2013, Worthington 2013, Risser 2009, WHO 2002, Janssen 2000).


  • Abciximab (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)
  • Ibuprofen (Safe substance and/or breastfeeding is the best option.)
  • Paracetamol (Safe substance and/or breastfeeding is the best option.)

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

C9 H8 O4 is Aspirin in Molecular formula.

Is written in other languages:

C9 H8 O4 is also known as


Main tradenames from several countries containing C9 H8 O4 in its composition:


Variable Value Unit
Oral Bioavail. 40 - 75 %
Molecular weight 180 daltons
Protein Binding 70 - 95 %
VD 0.15 l/Kg
Tmax 1 - 2 hours
7 (3 - 10) hours
M/P ratio 0.03 - 0.34 -
Theoretical Dose 0.004 - 0.3 mg/Kg/d
Relative Dose 0.3 - 1.1 %
Ped.Relat.Dose 0.004 - 0.75 %


  1. Datta P, Rewers-Felkins K, Kallem RR, Baker T, Hale TW. Transfer of Low Dose Aspirin Into Human Milk. J Hum Lact. 2017 May;33(2):296-299. Abstract
  2. Noviani M, Wasserman S, Clowse ME. Breastfeeding in mothers with systemic lupus erythematosus. Lupus. 2016 Aug;25(9):973-9. Abstract
  3. Davanzo R, Bua J, Paloni G, Facchina G. Breastfeeding and migraine drugs. Eur J Clin Pharmacol. 2014 Abstract
  4. Athavale MA, Maitra A, Patel S, Bhate VR, Toddywalla VS. Development of an in vitro cell culture model to study milk to plasma ratios of therapeutic drugs. Indian J Pharmacol. 2013 Abstract Full text (link to original source) Full text (in our servers)
  5. Worthington I, Pringsheim T, Gawel MJ, Gladstone J, Cooper P, Dilli E, Aube M, Leroux E, Becker WJ; Canadian Headache Society Acute Migraine Treatment Guideline Development Group. Canadian Headache Society Guideline: acute drug therapy for migraine headache. Can J Neurol Sci. 2013 Sep;40(5 Suppl 3):S1-S80. Review. Abstract Full text (in our servers)
  6. Rowe H, Baker T, Hale TW. Maternal medication, drug use, and breastfeeding. Pediatr Clin North Am. 2013 Feb;60(1):275-94. Abstract
  7. Sachs HC; Committee On Drugs. The transfer of drugs and therapeutics into human breast milk: an update on selected topics. Pediatrics. 2013 Sep;132(3):e796-809. Abstract Full text (link to original source) Full text (in our servers)
  8. Bloor M, Paech M. Nonsteroidal anti-inflammatory drugs during pregnancy and the initiation of lactation. Anesth Analg. 2013 Abstract
  9. Bell AD, Roussin A, Cartier R, Chan WS, Douketis JD, Gupta A, Kraw ME, Lindsay TF, Love MP, Pannu N, Rabasa-Lhoret R, Shuaib A, Teal P, Théroux P, Turpie AG, Welsh RC, Tanguay JF. The use of antiplatelet therapy in the outpatient setting: Canadian Cardiovascular Society Guidelines Executive Summary. Can J Cardiol. 2011 Abstract
  10. Chen LH, Zeind C, Mackell S, LaPointe T, Mutsch M, Wilson ME. Breastfeeding travelers: precautions and recommendations. J Travel Med. 2010 Jan-Feb;17(1):32-47. Abstract Full text (link to original source) Full text (in our servers)
  11. Risser A, Donovan D, Heintzman J, Page T. NSAID prescribing precautions. Am Fam Physician. 2009 Abstract Full text (link to original source) Full text (in our servers)
  12. Bar-Oz B, Bulkowstein M, Benyamini L, Greenberg R, Soriano I, Zimmerman D, Bortnik O, Berkovitch M. Use of antibiotic and analgesic drugs during lactation. Drug Saf. 2003 Abstract
  13. WHO / UNICEF. BREASTFEEDING AND MATERNAL MEDICATION Recommendations for Drugs in the Eleventh WHO Model List of Essential Drugs. Department of Child and Adolescent Health and Development (WHO/UNICEF) 2002 Abstract Full text (link to original source) Full text (in our servers)
  14. Spigset O, Hägg S. Analgesics and breast-feeding: safety considerations. Paediatr Drugs. 2000 Abstract
  15. Janssen NM, Genta MS. The effects of immunosuppressive and anti-inflammatory medications on fertility, pregnancy, and lactation. Arch Intern Med. 2000 Abstract Full text (link to original source) Full text (in our servers)
  16. Ito S, Blajchman A, Stephenson M, Eliopoulos C, Koren G. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993 May;168(5):1393-9. Abstract
  17. McGeorge BC, Steele MC. Allergic contact dermatitis of the nipple from Roman chamomile ointment. Contact Dermatitis. 1991 Feb;24(2):139-40. No abstract available. Abstract
  18. Unsworth J, d'Assis-Fonseca A, Beswick DT, Blake DR. Serum salicylate levels in a breast fed infant. Ann Rheum Dis. 1987 Abstract Full text (link to original source) Full text (in our servers)
  19. Bailey DN, Weibert RT, Naylor AJ, Shaw RF. A study of salicylate and caffeine excretion in the breast milk of two nursing mothers. J Anal Toxicol. 1982 Abstract
  20. Clark JH, Wilson WG. A 16-day-old breast-fed infant with metabolic acidosis caused by salicylate. Clin Pediatr (Phila). 1981 Abstract
  21. Findlay JW, DeAngelis RL, Kearney MF, Welch RM, Findlay JM. Analgesic drugs in breast milk and plasma. Clin Pharmacol Ther. 1981 May;29(5):625-33. Abstract
  22. Erickson SH, Oppenheim GL. Aspirin in breast milk. J Fam Pract. 1979 Abstract
  23. Terragna A, Spirito L. [Thrombocytopenic purpura in an infant after administration of acetylsalicylic acid to the wet-nurse] (Cited in: Aspirin. Toxnet-LactMed, access 10.06.2018) Minerva Pediatr. 1967 Abstract
  24. Harley JD, Robin H. "Late" neonatal jaundice in infants with glucose-6-phosphate dehydrogenase-deficient erythrocytes (Cited in: Aspirin. Toxnet-LactMed, access 10.06.2018). Australas Ann Med. 1962 Abstract

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