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Metformin Drug Interactions
Metformin drug interactions with other medications (such as certain decongestants, calcium channel blockers, and diuretics) can potentially lead to problems. Some of these drug interactions can make metformin less effective, increasing your chance of high blood sugar, or can increase the level of metformin in your blood, increasing your risk of side effects. Therefore, be sure to talk to your healthcare provider about any metformin drug interactions that may apply to you.
Metformin (Glucophage®) and metformin ER (Glucophage XR®) can potentially interact with many drugs. Some of the drugs that may lead to metformin interactions include:
- Certain decongestants, such as phenylephrine (Sudafed PE®) or pseudoephedrine (Sudafed®)
- Calcium channel blockers, such as:
- Amlodipine (Norvasc®)
- Diltiazem (Cardizem®, Dilacor®, Tiazac®)
- Felodipine (Plendil®)
- Isradipine (DynaCirc®)
- Nicardipine (Cardene®)
- Nifedipine (Adalat®, Procardia®)
- Nisoldipine (Sular®)
- Verapamil (Calan®, Verelan®)
- Cimetidine (Tagamet®)
- Corticosteroids, such as:
- Betamethasone (Celestone®)
- Cortisone
- Dexamethasone (Decadron®)
- Fludrocortisone (Florinef®)
- Hydrocortisone (Cortef®)
- Methylprednisolone (Depo-Medrol®, Medrol®)
- Prednisolone (Orapred®, Pediapred®)
- Prednisone
- Triamcinolone (Kenalog®, Aristospan®)
- Diuretics, such as:
- Acetazolamide (Diamox®)
- Amiloride (Midamor®)
- Bumetanide (Bumex®)
- Chlorothiazide (Diuril®)
- Chlorthalidone
- Ethacrynic acid (Edecrin®)
- Furosemide (Lasix®)
- Hydrochlorothiazide (Microzide®, HCTA)
- Metolazone (Zaroxolyn®)
- Torsemide (Demadex®)
- Triamterene (Dyrenium®, Dyazide®, Maxzide®)
- Estrogens
- Isoniazid
- Niacin (nicotinic acid, Niaspan®, Niacor®, Nicolar®)
- Oral contraceptives (birth control pills)
- Phenothiazine medications, including:
- Phenytoin (Dilantin®)
- Thyroid medications, such as levothyroxine (Levothroid®, Levoxyl®, Synthroid®, Tirosint®, Unithroid®), liothyronine (Cytomel®), thyroid (Armour Thyroid®), and Thyrolar®.
Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD