The Unfiltered Truth About Caffeine and Breastfeeding

By Danielle Facey, MSc & Breastfeeding Counsellor

I’ll be honest with you before we go any further. When I returned to work after having my son, I felt like I lived on coffee. Running on broken sleep, nursing through the night and showing up to consultations the next morning - caffeine was not a luxury for me. It was survival. So when I write about this topic, I am not writing from a place of detached clinical neutrality. I am writing as a breastfeeding mother, a Breastfeeding Counsellor and someone who made her own informed choices about caffeine whilst nursing. That context matters.

What I want to give you here is not a list of rules. It is the evidence. Because informed is empowered - and the only person who can decide what feels right for you, your baby and your unique circumstances is you.

A Quick Disclaimer

I always aim to present information with as much clarity and as little bias as possible. But in the spirit of full transparency: I do occasionally drink caffeinated drinks and I did throughout my breastfeeding journey. That does not change the science. It just means you are hearing it from someone who has lived it.

What Caffeine Does in Your Body

Caffeine is a central nervous system stimulant found in coffee, tea, chocolate, energy drinks and some medications. It enters your bloodstream quickly, sharpens alertness and causes your blood vessels to constrict. That last part - the vasoconstriction - is worth understanding, because it has specific implications for breastfeeding mothers (more on that below).

The caffeine content in common drinks varies more than most people realise (1):

• Coffee: 95 to 165mg per 8oz cup depending on bean and brew method

• Tea: 30 to 50mg per 8oz cup

• Dark chocolate: approximately 12mg per ounce

• Energy drinks: up to 300mg or more per serving

Caffeine adds up quickly when you factor in all sources. It is worth keeping a rough mental tally across the day.

How Much Actually Reaches Your Baby

This is where the evidence gets genuinely reassuring - and genuinely nuanced.

Caffeine appears in breast milk rapidly after ingestion, with peak levels occurring around one hour after consumption (2). At that peak, research estimates your exclusively breastfed baby receives roughly 7 to 10% of your weight-adjusted caffeine dose through milk (3,4). The half-life of caffeine in breast milk is approximately 6 to 7 hours, meaning levels decline steadily after that peak (2,5). That is a small amount. But it is not zero. And there are important caveats depending on your baby’s age and gestation.

Newborns and Premature Babies: A Different Picture

For most healthy babies over three months, moderate maternal caffeine intake is unlikely to cause problems. But newborns and preterm infants are a different story.

Preterm and newborn infants metabolise caffeine very slowly, and their serum caffeine levels can closely mirror their mother’s (6). Caffeine clearance does not reach adult levels until around 3 to 5 months of age - and in preterm infants, even later (6,7).

If your baby arrived early or is in the first weeks of life, this is the most important part of this blog for you. Lower is better in those early weeks. Not because a cup of tea will harm your baby, but because the margin is narrower and the evidence supports more caution.

What the Evidence Says About Behaviour

Fussiness, jitteriness and disrupted sleep are the symptoms most commonly associated with caffeine exposure through breast milk. But the evidence tells a specific story about dose.

These symptoms have only been documented at very high maternal intakes - equivalent to 10 or more cups of coffee daily (2). Studies looking at mothers consuming 5 cups per day found no measurable stimulation in infants aged 3 weeks and older (8). One cohort study found that maternal caffeine intake above 300mg daily was associated with slightly more nighttime awakenings in infants, but the difference was not statistically significant (9).

The honest summary: at moderate intake, behavioural effects in babies are unlikely. At very high intake, they are documented. Watch your own baby, no-one knows them like you do.

The Vasoconstriction Piece

This is the part that does not always make it into mainstream caffeine content - and it should.

Because caffeine constricts blood vessels, mothers who are already prone to Raynaud’s phenomenon or nipple vasospasm may find that high caffeine intake aggravates their symptoms (10). Nipple vasospasm typically presents as sharp, burning or throbbing nipple pain after feeds, often accompanied by colour changes in the nipple - white, blue or red.

If this sounds familiar, caffeine is worth discussing with an IBCLC. Reducing your intake is not guaranteed to resolve vasospasm, but it is a reasonable and evidence-informed place to start.

A Note About Iron

This one surprised me when I first came across it, and I think it deserves more airtime. Research shows that coffee intake above 450ml daily may reduce iron concentration in breast milk (11). In one study of nursing mothers, infants of high coffee consumers had lower iron levels and lower haemoglobin at one month postpartum (11).

Importantly, this is not caused by the caffeine itself - it is caused by compounds in coffee called chlorogenic acids, which inhibit iron absorption (10). This means switching to tea or other caffeinated drinks does not carry the same risk. But if coffee is your primary source of caffeine and you are drinking a lot of it, it is worth being aware of.

What the Guidelines Say

Recommendations vary by country, which itself tells you something about the level of certainty in the evidence:

• NHS (UK): up to 200mg per day (12)

• CDC (US) and European food safety authorities: up to 300mg per day (13,14)

Both consider moderate intake safe for most breastfeeding mothers and babies. Both recommend lower intake if your baby is premature or a newborn.

For context, 200mg is roughly one to two cups of filter coffee or two to three cups of tea. Energy drinks can take you over your daily limit in a single serving - worth knowing.

The Bottom Line

Caffeine does make its way into your breast milk. But the dose your baby receives at moderate maternal intake is small, the clearance is relatively fast and the evidence does not support the idea that a-coffee-a-day habit will harm a healthy baby.

What matters is context. Your baby’s age. Your own sensitivity. Whether you are experiencing nipple pain. How much you are actually consuming across all sources. You do not need anyone's permission to drink coffee while breastfeeding. You need information. And now you have it.

For evidence-based, heartled support in all things nursing, pumping and beyond, my Penguin debut ‘The Breastfeeding Survival Guide’ is available now.

With love,

Danielle

❤️

References:

1. Heckman MA, Weil J, Gonzalez de Mejia E. Caffeine (1, 3, 7-trimethylxanthine) in foods: a comprehensive review on consumption, functionality, safety, and regulatory matters. J Food Sci. 2010;75(3):R77-87.

2. Drugs and Lactation Database (LactMed). Caffeine [Internet]. Bethesda (MD): National Institute of Child Health and Human Development; 2006 [updated 2024 Jun 15; cited 2025 May]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501467/

3. Oo CY, Burgio DE, Kuhn RC, Desai N, McNamara PJ. Pharmacokinetics of caffeine and its demethylated metabolites in lactation: predictions of milk to serum concentration ratios. Pharm Res. 1995;12(2):313-6. [Foundational pharmacokinetic data; no subsequent study has superseded this.]

4. Stavchansky S, Combs A, Sagraves R, Delgado M, Bhatt-Mehta V. Pharmacokinetics of caffeine in breast milk and plasma after single oral administration of caffeine to lactating mothers. Biopharm Drug Dispos. 1988;9(3):285-99. [Foundational pharmacokinetic data; no subsequent study has superseded this.]

5. Berlin CM Jr, Denson HM, Daniel CH, Ward RM. Disposition of dietary caffeine in milk, saliva, and plasma of lactating women. Pediatrics. 1984;73(1):59-63. [Foundational pharmacokinetic data; no subsequent study has superseded this.]

6. McCreedy A, Bird S, Brown LJ, Shaw-Stewart J, Chen YF. Effects of maternal caffeine consumption on the breastfed child: a systematic review. Swiss Med Wkly. 2018;148:w14665.

7. Agunbiade S, Haruna M, Matsuzaki M, Shimpuku Y. Effects of caffeine on breastfeeding mothers and infants: a scoping review. Clin Lactation. 2024. doi:10.1891/CL-2023-0036

8. Elenberg-Alter Y, Batcir R. Caffeine consumption influence among lactating mothers on babies’ growth parameters during first 6 months of life: a prospective study. J Pediatr Gastroenterol Nutr. 2023;76(6):1049-50.

9. Purkiewicz A, Pietrzak-Fiecko R, Sörgel F, Kinzig M. Caffeine, paraxanthine, theophylline and theobromine content in human milk. Nutrients. 2022;14(11):2196.

10. McNamara PJ, Abbassi M. Neonatal exposure to drugs in breast milk. Pharm Res. 2004;21(4):555-66.

11. Santos IS, Matijasevich A, Domingues MR. Maternal caffeine consumption and infant nighttime waking: prospective cohort study. Pediatrics. 2012;129(5):860-8.

12. Breastfeeding Support. Coffee, caffeine and breastfeeding [Internet]. 2024 [cited 2025 May]. Available from: https://breastfeeding.support/coffee-caffeine-breastfeeding/

13. Muñoz LM, Lönnerdal B, Keen CL, Dewey KG. Coffee consumption as a factor in iron deficiency anemia among pregnant women and their infants in Costa Rica. Am J Clin Nutr. 1988;48(3):645-51. [Only published study on coffee, iron and breast milk; no subsequent data available.]

14. National Health Service. Breastfeeding and diet [Internet]. London: NHS; [cited 2025 May]. Available from: https://www.nhs.uk/conditions/baby/breastfeeding-and-bottle-feeding/breastfeeding-and-lifestyle/diet/

15. EFSA Panel on Dietetic Products Nutrition and Allergies. Scientific opinion on the safety of caffeine. EFSA J. 2015;13(5):4102.

16. Centers for Disease Control and Prevention. Maternal diet [Internet]. Atlanta: CDC; [cited 2025 May]. Available from: https://www.cdc.gov/breastfeeding/breastfeeding-special-circumstances/diet-and-micronutrients/maternal-diet.html