The relationship between metformin, a widely used medication, and tinnitus, the perception of phantom sounds, is complex. This article explores both reported instances of tinnitus as a potential side effect of metformin and emerging discussions regarding its possible therapeutic applications for certain types of tinnitus.
Understanding Metformin and Tinnitus
Metformin is a medication primarily prescribed for individuals with type 2 diabetes. It functions as a hypoglycemic agent, lowering blood sugar levels. It is often a first-line treatment for managing blood glucose in diabetic patients.
Tinnitus is characterized by the sensation of hearing noises in one or both ears that are not produced by an external source. These phantom sounds can manifest as ringing, buzzing, hissing, whistling, or clicking. Tinnitus is a neurological disorder that can significantly affect a patient’s quality of life.
Tinnitus as a Reported Side Effect of Metformin
Some individuals have reported experiencing tinnitus after initiating or increasing their metformin dosage. These accounts often describe the sound as a low-level hiss or ringing.
Adverse drug reaction databases have also documented instances of tinnitus associated with metformin use. The Malaysian Adverse Drug Reaction database and the World Health Organization (WHO) ADR database have recorded such occurrences. These databases collect spontaneous reports from healthcare professionals and patients, contributing to a broader understanding of potential side effects.
A possible pharmacological explanation for tinnitus in metformin users involves vitamin B12 deficiency. Higher doses and longer durations of metformin use have been linked to an increased risk of vitamin B12 deficiency. This deficiency can lead to various neurological symptoms, including neuropathy and cognitive impairment, which may encompass tinnitus. Metformin is thought to interfere with the absorption of vitamin B12 in the terminal ileum, potentially by affecting the calcium-dependent binding of the intrinsic factor-vitamin B12 complex.
Metformin’s Emerging Therapeutic Potential for Tinnitus
Conversely, recent discussions and self-reports suggest that low-dose metformin might have a role in managing certain forms of tinnitus. This includes idiopathic tinnitus, where the cause is unknown, and tinnitus associated with long COVID. One self-report discusses the author’s experience managing idiopathic tinnitus with a low-dose metformin approach.
The exact mechanism by which metformin might alleviate tinnitus remains unclear. While some studies acknowledge tinnitus as a possible side effect of metformin, other research indicates that metformin users might experience reduced growth of vestibular schwannomas. Vestibular schwannomas are benign tumors that can cause hearing loss and tinnitus.
This potential for reduced tumor growth suggests a broader therapeutic application for metformin beyond diabetes management. Research indicates metformin may offer hearing protection against various inner ear insults, including radiation, noise, and certain chemotherapy drugs. These observations hint at metformin’s potential in addressing auditory issues, though more investigation is needed to confirm these findings.
Key Considerations and Ongoing Research
The relationship between metformin and tinnitus is complex, with evidence suggesting both a potential side effect and an emerging therapeutic role. Ongoing research is necessary to fully elucidate the physiological mechanisms involved in both scenarios.
Further robust, controlled clinical trials are needed to confirm the reported side effects and investigate the therapeutic potential of metformin for tinnitus. Individual responses to medication can vary significantly. Patients experiencing new or worsening tinnitus symptoms while on metformin should consult their healthcare professional to discuss their concerns and evaluate their treatment plan.