Metformin Hydrochloride Label Adds Boxed Warning for Lactic Acidosis

On January 1, 2026, the U.S. Food and Drug Administration (FDA) revised the label for Metformin Hydrochloride to include a new boxed warning regarding the risk of lactic acidosis. The warning, titled "WARNING: LACTIC ACIDOSIS," states that postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. It further notes that the onset of this condition is often subtle.

What this means

The implementation of a boxed warning on the Metformin Hydrochloride label is a significant update for healthcare providers and patients. The warning explicitly details the severe consequences observed in postmarketing cases of metformin-associated lactic acidosis, including death, hypothermia, hypotension, and resistant bradyarrhythmias. This underscores the critical, life-threatening nature of this adverse event. The label also emphasizes that the onset of metformin-associated lactic acidosis is often subtle, which can complicate early diagnosis and intervention. Clinicians must therefore maintain a high degree of suspicion for this condition, particularly in patients with predisposing factors such as renal impairment, concomitant use of certain drugs, or conditions that may lead to hypoperfusion and hypoxemia. The subtle presentation means that symptoms may be nonspecific, requiring careful clinical judgment. Healthcare professionals are advised to thoroughly review patient medical histories for contraindications to Metformin Hydrochloride and to educate patients on the signs and symptoms of lactic acidosis, instructing them to seek immediate medical attention if these occur. This label revision aims to enhance patient safety by ensuring that the serious risks associated with Metformin Hydrochloride are clearly communicated and understood by prescribers.

Source

This information is based on a label revision by the U.S. Food and Drug Administration (FDA), effective January 1, 2026. The updated label for Metformin Hydrochloride is available on dailymed.nlm.nih.gov.