On 2026-06-26, the U.S. Food and Drug Administration (FDA) revised the label for Metformin Hydrochloride to include a Boxed Warning. This significant update highlights the risk of lactic acidosis, a serious adverse event that has been associated with postmarketing cases resulting in death.
Background
A Boxed Warning, also known as a black box warning, is the strongest warning that the FDA requires for prescription drug labels. It is used to call attention to serious or life-threatening risks associated with a drug. Metformin Hydrochloride is a widely prescribed medication, primarily used in the management of type 2 diabetes. It is also a component in several combination drug products, such as Invokamet and Invokamet XR, which combine metformin with canagliflozin. The addition of this warning underscores a critical safety concern that warrants careful consideration by healthcare providers and patients.
What this means
The new Boxed Warning for Metformin Hydrochloride serves as a crucial alert regarding the potential for lactic acidosis. This severe metabolic complication has been observed in postmarketing cases and can be fatal. The warning specifically details that metformin-associated lactic acidosis has led to outcomes such as death, hypothermia, hypotension, and resistant bradyarrhythmias. Healthcare professionals are advised that the onset of this condition can be subtle, making early recognition challenging but vital. It is imperative for clinicians to be vigilant for symptoms and risk factors for lactic acidosis when prescribing or monitoring patients on Metformin Hydrochloride. This label change reinforces the importance of patient education regarding potential symptoms and when to seek immediate medical attention, aiming to mitigate the risks associated with this serious adverse event.
Source
This label revision was made effective on 2026-06-26 by the U.S. Food and Drug Administration (FDA). The details of the Boxed Warning are available on DailyMed (dailymed.nlm.nih.gov), an official database of drug labels and information, under the set ID 552ad61d-bafd-478d-e063-6294a90a02f9.