The short answer
Not known in people. We found no study of punarnava taken with metformin. In a rat study from Vadodara, a punarnava extract lowered high blood sugar in diabetic rats, with metformin used as the comparison. No group of rats got both.
If punarnava lowers sugar in people too, it could add to diabetes medicines. The metformin label warns that low sugar is more likely when metformin is combined with insulin or drugs such as glimepiride. If you take diabetes medicine, tell your prescribing doctor before you start punarnava, and ask whether you should check your sugar more often.
Metformin is sold in India as Glycomet. Glycomet-GP also contains glimepiride, a second diabetes medicine.
At a glance
| What was seen | How it may work | Direction | Evidence |
|---|---|---|---|
| Lower blood sugar in diabetic rats[1] | Not established | Could add to sugar-lowering medicines | Animal |
No listing is not a clearance. A missing interaction here never means a combination is safe.
The evidence, study by study
Rat study, Vadodara, 2011 Animal
Rats made diabetic with a chemical (alloxan) were given an ethanol extract of punarnava, 500 mg per kg of body weight, or metformin, for 30 days. The punarnava extract lowered their high blood sugar and kept kidney salt balance and antioxidant markers closer to normal. The abstract gives neither the number of rats nor the size of the fall in sugar. No rats got punarnava and metformin together, so this was a comparison, not an interaction study.[1]
What your doctor may watch for
- Blood sugar, especially if you also take insulin or a sulfonylurea such as glimepiride or gliclazide. The metformin label warns of a higher risk of low sugar with these.[2]
- Kidney function, which your doctor already checks on metformin.[2]
What to tell your prescribing doctor
You can read this out, or show them this page:
“I am taking, or planning to take, punarnava (name of product, dose) along with metformin. A rat study found punarnava lowers blood sugar. Should I check my sugar more often?”
Withheld until review
Questions people ask
Can punarnava be used instead of metformin?
We found no study in people that tested this. In the rat study, metformin was only the yardstick, and rats are not people. Any change to your diabetes medicine is a decision for your prescribing doctor.[1]
I take Glycomet-GP. Does that change anything?
Glycomet-GP contains glimepiride as well as metformin. The metformin label says low sugar is more likely with that kind of combination, so tell your doctor about any sugar-lowering herb you add.[2]
Related
Punarnava and blood pressure medicines
Not studied in people. Lab and animal work suggests punarnava acts on urine flow and blood vessels, which could add to BP medicines.
ConditionType 2 diabetes (sugar): what Ayurveda offers
Some herbs, such as methi and karela, lowered HbA1c a little in trials. Taken with diabetes medicines, they can add to the risk of low sugar.
InteractionGokshura (gokhru) and metformin
A tribulus extract lowered blood sugar in one trial, so it could add to metformin. We found no study of the two taken together.
Sources
- Singh PK, Baxi D, Doshi A, A V R. Antihyperglycaemic and renoprotective effect of Boerhaavia diffusa L. in experimental diabetic rats. J Complement Integr Med. 2011;8. PMID 22754925.
- Metformin hydrochloride tablets, US prescribing information, Warnings and Precautions (DailyMed).
Updated 4 November 2026
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