How to use it
Take metformin with or without food with a full glass of water. (People with type 2 diabetes have an increased risk of developing kidney stones.) Do not crush, chew, or divide the tablets. Follow all instructions from your health care provider.
Store metformin at room temperature in its container, tightly closed, away from light, excess heat, and moisture. Don't store it in the bathroom or near a kitchen sink, dishwasher, or oven. Keep metformin away from children and pets.
Dosing
Metformin comes as a tablet or an oral solution, with a typical starting dose of 500 mg. Your health care provider will customize dosing based on various factors (including your weight and how well you tolerate the medication) and may increase your dose over time, usually not more than once every one to two weeks.
If you miss a dose, take the dose you missed as soon as you remember. If it's almost time for your next dose, just skip the dose you missed. Do not take a double dose.
Side effects
Take metformin under a clinician’s care. Studies show long-term use of metformin may, in rare cases, lead to complications including pancreatitis, hepatitis, abnormal blood clotting, vitamin B12 deficiency, and reactive hypoglycemia.
Additionally, metformin may stimulate ovulation in those with PCOS or who are premenopausal, which may increase the risk of unintended pregnancy. If you’re in a sexual relationship that could result in pregnancy, use at least one form of birth control unless you’re planning on getting pregnant.
Black Box Warning
The FDA has a black box warning on metformin for lactic acidosis. This rare, but potentially fatal, condition happens when too much lactic acid builds up in the bloodstream. It can lead to low blood pressure, fast, shallow breathing, increased risk of heart failure, and even death.
Risk factors include renal impairment, concomitant use of certain drugs, age ≥65 years old, radiological studies with contrast, surgery and other procedures, hypoxic states, excessive alcohol intake, and hepatic impairment. Lactic acidosis is a medical emergency and requires immediate treatment in the hospital.
Precautions
Take metformin under a clinician’s care. Studies show long-term use of metformin may, in rare cases, lead to complications including pancreatitis, hepatitis, abnormal blood clotting, vitamin B12 deficiency, and reactive hypoglycemia.
Additionally, metformin may stimulate ovulation in those with PCOS or who are premenopausal, which may increase the risk of unintended pregnancy. If you’re in a sexual relationship that could result in pregnancy, use at least one form of birth control unless you’re planning on getting pregnant.
Interactions
Some drugs and supplements can interact with metformin, including:
- Insulin
- Other diabetes medications
- Drugs that increase blood sugar
- Hormone replacement therapy
- Hormonal contraceptives
- ACE inhibitors
- Asthma and cold medicine
- Morphine
- Anti-nausea drugs
- Beta-blockers
- Corticosteroids and oral steroids
- Antipsychotic medications
- Thyroid medications
- Diuretics
- Seizure medications
- Carbonic anhydrase inhibitors
- Ranolazine (Ranexa®)
- Vandetanib (Caprelsa®)
- Dolutegravir (Tivicay®)
- Cimetidine (Tagamet® HB)
- Vitamin K antagonists (warfarin)
You should not drink alcohol while taking metformin because it can lower blood sugar and may cause blood sugars to fall too fast, leading to fainting and dizziness. Also, avoid consuming sugary foods and drinks and foods with a high glycemic load while taking metformin.
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