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Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-.

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Drugs and Lactation Database (LactMed) [Internet].

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Brewer’s Yeast

Last Revision: December 20, 2021.

Estimated reading time: 2 minutes

Drug Levels and Effects

Summary of Use during Lactation

The dead yeast cells of brewer’s yeast (Saccharomyces cerevisiae) is used as a dietary supplement to enhance milk production. No scientifically valid studies in humans have been performed that establish an effect of brewer’s yeast on milk supply. Although studies in ruminants indicate that brewer’s yeast might increase milk supply, the effect is attributed to improved nutrition (increases in vitamin B and chromium) rather than any specific effect on lactation.[1] Some side effects, mostly gastrointestinal, have been reported by nursing mothers taking brewer’s yeast. There are wide variations in the content of brewer’s yeast products.[1]

Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.

Drug Levels

Maternal Levels. Relevant published information was not found as of the revision date.

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

In a survey of 108 nursing mothers in South Africa, one woman reported cramps in her infant after she used brewer’s yeast as a galactogogue.[2]

Effects on Lactation and Breastmilk

In a survey of nursing mothers in Australia, 592 mothers were taking brewer’s yeast as a galactogogue. On average, mothers rated brewer’s yeast as slightly less than “moderately effective” on a Likert scale. Sixty-five mothers (11%) taking brewer’s yeast reported experiencing an adverse reaction, most commonly weight gain, stomach cramps, dry mouth and nausea. Twelve (2%) reported having more than one adverse effect.[3]


Jia LL, Brough L, Weber JL. Saccharomyces cerevisiae yeast-based supplementation as a galactagogue in breastfeeding women? A review of evidence from animal and human studies. Nutrients. 2021;13:727. [PMC free article: PMC7996189] [PubMed: 33668808]
Steyn N, Zunza M, Decloedt EH. A cross-sectional descriptive study of breastfeeding behaviour and galactogogue use among private-sector patients in Cape Town, South Africa. S Afr J Obstet Gynaecol. 2017;23:20–3. [CrossRef]
McBride GM, Stevenson R, Zizzo G, et al. Use and experiences of galactagogues while breastfeeding among Australian women. PLoS One. 2021;16:e0254049. [PMC free article: PMC8248610] [PubMed: 34197558]

Substance Identification

Substance Name

Brewer’s Yeast

Scientific Name

Saccharomyces cerevisiae

Drug Class

Breast Feeding


Complementary Therapies


Disclaimer: Information presented in this database is not meant as a substitute for professional judgment. You should consult your healthcare provider for breastfeeding advice related to your particular situation. The U.S. government does not warrant or assume any liability or responsibility for the accuracy or completeness of the information on this Site.


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