Metformin

Oral health effects

• Metallic taste (dysgeusia)

  Some patients report a transient metallic or altered taste.

  Clinical management: Usually self-limiting; reassure and rule out other causes.

• Indirect periodontal/caries risk via glycemic control

  These agents do not act directly on the mouth, but the underlying diabetes (and how well it is controlled) strongly influences periodontal disease, healing, and infection risk.

  Clinical management: Reinforce that good glycemic control supports periodontal health; coordinate care and note HbA1c.

• Vitamin B12 deficiency–related oral changes (glossitis, angular cheilitis)

  Metformin lowers vitamin B12 levels (subnormal levels in ~7% of patients in 29-week trials, per the label); long-term deficiency can present orally as a smooth, red, sore tongue (atrophic glossitis), angular cheilitis or aphthous-like ulcers.

  Clinical management: In long-term metformin users with an unexplained sore/burning or smooth red tongue, angular cheilitis or recurrent ulcers, suggest the physician check B12 status (and a blood count) rather than treating as a purely local problem.