Breast and nipple pain when someone is breastfeeding is sometimes caused by thrush, an infection from Candida albicans, which can cause issues if left untreated.^{1 2} Breastfed babies can also develop thrush in their mouths.

If thrush develops in a baby or their parent, there are several healing protocols that someone can follow.³ Please consult a healthcare provider and/or other local resources for more information about treatment options.

If a lactating person has a Candida infection it is suggested that they wash clothes that come into contact with the affected areas, like bras, reusable nursing pads, etcetera, in very hot water.^{4 5 6} ((NHS – Thrush)) ((Some research indicates that microwaving may also inactivate Candida if the clothes are damp as most microorganisms are inactivated by moist heat (ie. steam) 121°C/252.5ºF for 15-30 min. Government of Canada – Pathogen Safety Data Sheets: Infectious Substances – Candida albicans))

A Candida infection can also be transmitted via skin-to-skin contact, unclean hands, shared towels, and sexual contact. ((Odds, 1981. Genital Candidosis)) This does however not mean that the other person will develop thrush. ((Cleveland Clinic – Thrush))

Using expressed milk
Keeping breastfeeding or feeding expressed milk while under treatment is considered safe. When expressing milk, it is suggested to thoroughly clean supplies in order to prevent cross-contamination.

Some recommend that milk that has been expressed and stored (frozen) should not be used once treatment is done so as to avoid re-contamination. This is probably based on the fact that in food science, freezing does not eliminate Candida but only slows down its growth. Other sources suggest pasteurizing, scalding, or boiling expressed milk to avoid re-contamination with Candida after treatment because food safety shows that heating foods destroys yeast to temperatures of ≥ 60ºC/140°F.⁷

We can however find no evidence that suggests that Candida in expressed milk can cause a new infection. Literature has suggested candida can be a problem in milk because it can be passed from person to person, and can live in fabrics and porous materials. But yeast found in human milk is exposed to lactoferrin, which inactivates it. ^{8 9} The amount of yeast needed to cause infection is also high, so recommendations for dilution with fresh milk introduce both dilution and even more exposure to lactoferrin.

If one were to heat treat expressed milk out of Candida concerns, sources either say that Candida is killed at 50ºC/122ºF,¹⁰ or by boiling, (100ºC/212ºF),¹¹ scalding (82-85ºC/180-185ºF), which heats milk just¹² until it begins to steam,¹³ or pasteurizing (62.5°C/145°F for 30 minutes or 72ºC/161.6ºF for 15 초).¹⁴ As you can see these temperatures are vastly different, with the first one not meeting food safety standards.

If someone plans to heat-treat milk due to a Candida infection it is important to note that heat-treating human milk reduces lactoferrin as well as important anti-infective factors and enzymatic activities. Therefore, combined with the lack of evidence that Candida in milk causes a new infection, heat treatment does not seem to be the most logical route to take. Heat treating can also activate spores.

If a candida infection develops while being a donor, disclose this information to the recipient, especially when donating to a premature or immuno-compromised baby. Families may choose to continue to receive milk if their child is otherwise healthy and the donor is under treatment. If choosing to accept milk from a donor who has thrush, recipients should educate themselves on how to treat thrush should it develop in their child due to contamination from improper handling.

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1. NHS – Oral thrush (Mouth thrush) ↩︎
2. NHS – Breastfeeding and thrush ↩︎
3. IBC – Candida Protocol ↩︎
4. Illinois DHS – Trush – Yeast infection ↩︎
5. Older studies seem to indicate that it takes the temperature to be over 70ºC/158ºF and hot ironing to completely eradicate Candida. Rashid, 외. 편집자에게 보내는 편지. British Journal of Venereal Diseases. Survival of Candida albicans on fabric after laundering The authors add that this may be too impractical in a home setting and they suggest using an antifungal disinfectant in the laundry. ↩︎
6. Per University Midwifery Associates. 2005. Yeast and Breastfeeding using vinegar to inhibit the fungus to grow is another suggestion as thrush cannot thrive in acidic conditions. Adding 120–240ml (½–1 cup) of distilled white vinegar to baths and in final rinses in washing machines can help mitigate the fungus. 하지만, research shows that C. albicans can actively neutralize the environment from either acidic or alkaline pHs depending on need, which means that vinegar alone may not be enough Slavena Vylkova, 외. 2011. The Fungal Pathogen Candida albicans Autoinduces Hyphal Morphogenesis by Raising Extracellular pH ↩︎
7. University of California Cooperative Extension – Food Safety Basics ↩︎
8. Y. Andersson, 외. 2000. Lactoferrin is responsible for the fungistatic effect of human milk ↩︎
9. Hashem Al-Sheikh. 2009. Effect of Lactoferrin and Iron on the Growth Human Pathogenic Candida Species ↩︎
10. Odds. 1988. 2nd Edition. Candida and Candidosis. Print, p.14: The pathogenic Candida species usually die within minutes at temperatures above 50ºC although in one study C. albicans in a rich nutrient broth took 1h to die at 70ºC and it survived the temperatures within composted sewage. ↩︎
11. Mohrbacher and Stock. 2003. The Breastfeeding Answer Book. Print. ↩︎
12. See Bacteria ↩︎
13. UnityPointHealth – Yeast Infection ↩︎
14. Wambach and Spencer. 2021. Breastfeeding and Human Lactation. p 544 ↩︎