Parsley is widely believed to decrease breast milk supply, but no clinical trials in humans have confirmed this effect. The claim comes from traditional use and a theoretical link to prolactin, the hormone that drives milk production. In practice, the small amounts of parsley used in cooking are very unlikely to affect your supply at all.
What the Evidence Actually Shows
The idea that parsley suppresses lactation has circulated for generations across many cultures. Lactation consultants and herbal references often list it alongside sage, peppermint, and jasmine as a potential “anti-galactagogue,” meaning a substance that reduces milk production. A commercial herbal supplement used in animal research (Stop Lactin) was formulated specifically around the supposed lactation-suppressing properties of sage and parsley. But when the National Institutes of Health reviewed the evidence for its Drugs and Lactation Database (LactMed), the conclusion was clear: “no scientifically valid clinical trials support this use.”
The physiological mechanism by which parsley might reduce milk has never been established either. Parsley is believed to lower prolactin levels, which would in theory slow milk production, but researchers have noted that no study has actually documented how or whether this happens in the body. The claim remains plausible but unproven.
Culinary Parsley vs. Concentrated Supplements
There’s a meaningful difference between sprinkling parsley on your pasta and taking concentrated parsley capsules or drinking multiple cups of strong parsley tea daily. The concern about milk supply centers on large, repeated doses, not the amounts you’d encounter as a garnish or ingredient in a recipe. A tabouleh salad or a handful of fresh parsley in a soup is not going to tank your supply.
If you’re breastfeeding and enjoy parsley in your meals, there’s no established reason to avoid it. The quantities used in normal cooking fall far below what any traditional protocol would recommend for milk suppression. The worry mostly applies to women deliberately consuming parsley in supplement form or as a concentrated tea over several days.
How Parsley Compares to Other Herbs
Among herbs traditionally used to reduce milk supply, sage has the strongest reputation and slightly more (though still limited) research behind it. Peppermint oil, chasteberry, and jasmine flowers are also commonly cited. Parsley sits in this same category of traditional remedies that lactation professionals mention but that lack rigorous human data.
Interestingly, parsley also appears in some herbal mixtures designed to do the opposite: increase milk supply. A study of 158 breastfeeding mothers in Iran used a proprietary herbal drop containing parsley alongside fennel, anise, cumin, and black seed as a supposed galactagogue (milk booster). This contradictory use highlights how thin the evidence really is. The same herb gets credited with both increasing and decreasing supply depending on the tradition and the formulation.
What This Means if You’re Trying to Reduce Supply
If you’re dealing with oversupply or weaning and came across parsley as a natural option, know that its effectiveness is anecdotal. Some women report that drinking parsley tea or taking parsley supplements helped reduce engorgement or slow production during weaning, but these reports can’t be separated from the natural decline in supply that comes with less frequent nursing or pumping.
The most reliable way to reduce milk supply is to gradually decrease how often you nurse or pump. Your body produces milk on a supply-and-demand basis, so removing less milk signals your body to make less. If you want to try parsley tea alongside that process, there’s no strong evidence it will help, but occasional use in moderate amounts is generally considered low-risk.
What This Means if You’re Worried About Your Supply
If you landed here because you’re breastfeeding and wondering whether the parsley in your dinner could hurt your supply, the short answer is no. Normal culinary use has not been shown to cause any measurable change in milk production. The concern applies to concentrated, repeated doses taken with the specific intention of suppressing lactation, and even then, the effect is unproven. You don’t need to scan ingredient lists or skip your favorite recipes.