Goat's rue

BotanicalBest with a meal

What is it

Goat's rue (Galega officinalis), also called French lilac, is a legume historically used in folk medicine for diabetes and to support milk supply in breastfeeding. It contains guanidine compounds that inspired the development of metformin.

Evidence for 2 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Lactation support (traditional galactagogue)

Mixed Evidence

Traditional and observational evidence exists; rigorous trials are lacking.

Blood glucose support

Mixed Evidence

Historical interest led to metformin's development; goat's rue itself is not recommended as a glucose-lowering treatment.

How it works

Galegine and related guanidine compounds in goat's rue have mild blood-glucose-lowering activity in animal studies. They are structurally related to metformin, but goat's rue itself contains a variable mixture of compounds and has a narrower safety window than the purified drug. For lactation, traditional use as a galactagogue is supported by small observational data and tradition; high-quality trials are sparse.

Dosage

There is no RDA. Traditional doses are roughly 1-2 g of dried herb in tea or equivalent extract, taken in divided doses. DSLD does not provide a median dose for this entry.

When and how to take it

Take with meals to reduce GI upset and stabilize blood glucose. Short courses are preferred over chronic daily use.

1 commercial form

Compare the main delivery options and what they’re best suited for.

Galega officinalis herb extract / glycerite

Liquid and powdered extracts of the aerial parts.

Alkaloid and guanidine content varies by preparation.

Safety

Raw plant material has caused fatal toxicity in livestock at high intakes. Properly prepared herbal supplements at moderate doses are generally tolerated, but the toxicity profile means caution is warranted. Hypoglycemia is a possible risk.

Who should be cautious

Avoid in pregnancy. Use only short-term in breastfeeding under clinician guidance if at all. Caution in diabetes (risk of hypoglycemia, especially combined with medications) and in children.

Interactions

Possible additive effects with metformin, insulin, and other glucose-lowering drugs. Theoretical interaction with serotonergic drugs based on alkaloid content; clinical evidence is limited.

Frequently asked questions

Does goat's rue boost milk supply?⌄

It is a traditional galactagogue with modest observational support. Standard lactation strategies (feeding, latch, hydration) come first.

Is it related to metformin?⌄

Yes. Galegine in goat's rue inspired the chemistry that led to metformin, but the herb itself is not a substitute for the drug.

References

Goat's rue on NIH DSLD (US supplement label database) — NIH Dietary Supplement Label Database link

Research on Goat's rue (PubMed search) — PubMed link

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Evidence-based·How we grade evidence

Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.