Is Glucomannan Safe with Metformin?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Take Metformin at least 2 hours before or 4 hours after Glucomannan. Do not take them simultaneously. Inform your pharmacist about this supplement to optimize your dosing schedule.
Why this interaction occurs
Glucomannan is a viscous soluble fiber that significantly slows gastric emptying and intestinal absorption. It may reduce the rate and extent of Metformin absorption, potentially decreasing its therapeutic efficacy in blood glucose control.
Evidence
Evidence level: moderate.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 432,898 reports mentioning Metformin. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Metformin + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Glucomannan interactions → · All Metformin interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.