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Limited evidenceWomen's health

Goat's Rue

A traditional galactagogue with no trial of its own. It has only ever been tested inside a combination product, and reviewers rate the whole herbal galactagogue literature as low certainty.

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What the science says

  • Only tested as part of a combination Limited evidence

    The randomized evidence comes from a product combining silymarin-phosphatidylserine with Galega. In 100 mothers of preterm infants, daily milk production was 200 mL versus 115 mL on placebo over the first month. The contribution of goat's rue alone cannot be separated out.

  • Low-certainty evidence across herbal galactagogues Limited evidence

    A 2026 systematic review of 10 randomized trials in mothers of preterm babies rated all the evidence low certainty. The silymarin-phosphatidylserine-Galega combination was among those with a measurable milk volume increase (mean difference 105 mL, 95% CI 27–183) by day 7.

Dosage & safety

Studied doseTraditional use is 1–2 g of dried herb as tea, or 1–2 mL of tincture, up to three times daily. No dose of goat's rue on its own has ever been tested in a trial.
SafetyGalega officinalis contains guanidine derivatives — the chemical ancestors of metformin — and can lower blood sugar, which matters if you take diabetes medication. The fresh plant is toxic to grazing livestock, and hypoglycemia has been reported in a breastfed infant whose mother used a galactagogue tea containing it. Not for use in pregnancy. Low milk supply has many causes; have it assessed by a lactation consultant before reaching for a herb.

How to take it

TimingTraditionally taken two or three times a day, spread out rather than in one dose.
With food?Take it with food, which softens both the stomach upset and the blood-sugar dip.
Worth knowingHypoglycemia has been reported in a breastfed infant whose mother drank a galactagogue tea containing it, so this is not a harmless herbal tea if you are nursing.

Interactions

With medications

  • insulin and oral diabetes medication (metformin, sulfonylureas, gliclazide)

    The guanidine derivatives in goat's rue lower blood glucose and can add to the drug's effect, causing hypoglycemia. do not combine without medical supervision and blood glucose monitoring

With other supplements

  • other glucose-lowering supplements (berberine, cinnamon, fenugreek, gymnema)

    Additive blood-sugar lowering that is easy to overshoot. do not stack them

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does goat's rue increase breast milk supply?

Unproven: goat's rue has no trial of its own and has only been tested inside a combination product with silymarin-phosphatidylserine, rated low-certainty evidence. The effect of goat's rue alone cannot be separated out.

Is goat's rue safe while breastfeeding?

Goat's rue can lower blood sugar, and hypoglycemia has been reported in a breastfed infant whose mother drank a galactagogue tea containing it, so it is not a harmless herbal tea. Have low milk supply assessed by a lactation consultant first; it is not for use in pregnancy.

Can you take goat's rue with metformin or diabetes medication?

Not without medical supervision: goat's rue contains guanidine derivatives, the chemical ancestors of metformin, and can add to diabetes drugs to cause hypoglycemia. Do not stack it with other glucose-lowering supplements such as berberine or fenugreek either.

How much goat's rue tea per day?

Traditional use is 1–2 g of dried goat's rue as tea, or 1–2 mL of tincture, up to three times daily, but no dose of goat's rue on its own has ever been tested in a trial.

Scientific references

Related in Women's health

Herbal medicines: what the evidence says (335)