Metformin Hydrochloride Label Receives New Boxed Warning for Lactic Acidosis

The U.S. Food and Drug Administration (FDA) announced a new boxed warning for Metformin Hydrochloride on 2026-04-16. This significant label revision highlights the risk of lactic acidosis, a serious metabolic complication associated with the drug. Postmarketing cases of metformin-associated lactic acidosis have been reported, leading to severe outcomes including death, hypothermia, hypotension, and resistant bradyarrhythmias.

Background

Metformin Hydrochloride is a widely prescribed medication, commonly used in the management of type 2 diabetes. The addition of a boxed warning by the FDA signifies a critical safety concern that prescribers and patients must be aware of. Boxed warnings, also known as black box warnings, are the strongest warnings the FDA requires for prescription drug products when there is reasonable evidence of an association of a serious hazard with the drug.

Metformin is also available in combination products, such as canagliflozin and metformin hydrochloride (e.g., Invokamet, Invokamet XR), which combine metformin with an SGLT2 inhibitor like canagliflozin. The boxed warning specifically addresses the risks associated with the metformin component.

What this means

The addition of a boxed warning for lactic acidosis on the Metformin Hydrochloride label underscores the importance of careful patient selection, monitoring, and education for individuals prescribed this medication. Clinicians should be vigilant for signs and symptoms of lactic acidosis, which can often be subtle in onset. Patients should be informed about the symptoms of lactic acidosis and advised to seek immediate medical attention if they experience them. This label update reinforces the need for a thorough risk-benefit assessment when prescribing metformin, especially in patients with predisposing factors for lactic acidosis.

Source

This information regarding the boxed warning for Metformin Hydrochloride was issued by the FDA on 2026-04-16. The label revision is documented on DailyMed, a service of the National Library of Medicine, at dailymed.nlm.nih.gov.