Metformin
Brand: Glucophage (discontinued; Glumetza, Fortamet brands)
Boxed warning · ISMP high-alert drug
Lactic acidosis, rare but often fatal, most likely with kidney impairment, liver disease, alcohol excess, or contrast dye.
- Caution
- Hold before and 48 hours after iodinated contrast; vitamin B12 deficiency with long-term use.
- Pregnancy
- Commonly continued in pregnancy and used for gestational diabetes under supervision.
Common side effects
- Diarrhea
- Nausea
- Stomach upset
- Metallic taste
- Vitamin B12 deficiency (long-term)
Key interactions
- Alcohol raises lactic acidosis risk
- Hold before IV contrast imaging
- Caution with other drugs affecting kidneys
- May add to low blood sugar with insulin
Counseling points
- Take with meals to reduce stomach upset
- Do not crush extended-release tablets
- Report muscle pain, weakness, or trouble breathing
- Limit alcohol
- Continue diet and exercise
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