- Rarely, metformin may cause an acid health problem in the blood (lactic acidosis). The risk of lactic acidosis is higher in people with kidney problems and in people who take certain other drugs like topiramate. The risk is also higher in people with liver problems or heart failure, in older people (65 or older), or with alcohol use. If lactic acidosis happens, it can lead to other health problems and can be deadly. Lab tests to check the kidneys may be done while taking this drug. Talk with the doctor.
- Call your doctor right away if you have signs of too much lactic acid in the blood (lactic acidosis) like fast breathing, fast or slow heartbeat, a heartbeat that does not feel normal, very bad upset stomach or throwing up, feeling very sleepy, shortness of breath, feeling very tired or weak, very bad dizziness, feeling cold, or muscle pain or cramps.
- Do not take this drug if you have a very bad infection, low oxygen, or a lot of fluid loss.
- Talk with your doctor before you drink alcohol.
- If you are having an exam or test with contrast or have had one within the past 48 hours, talk with your doctor.
- Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
- It is used to lower blood sugar in patients with high blood sugar (diabetes).
- It is used to lower the chance of death from heart disease in certain people.
- If you have an allergy to this drug or any part of this drug.
- If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
- If you have any of these health problems: Acidic blood problem or type 1 diabetes.
- If you have any of these health problems: Kidney disease or liver disease.
- If you have had a recent heart attack or stroke.
- If you are not able to eat or drink like normal, including before certain procedures or surgery.
- If you are pregnant or may be pregnant. Do not take this drug if you are in the second or third trimester of pregnancy.
- If you are breast-feeding. Do not breast-feed while you take this drug.
- Do not drive if your blood sugar has been low. There is a greater chance of you having a crash.
- To lower the chance of feeling dizzy or passing out, rise slowly over a few minutes when sitting or lying down. Be careful climbing stairs.
- Be careful in hot weather or while being active. Drink lots of fluids to stop fluid loss.
- If loose stools (diarrhea) happen or you are throwing up, call your doctor. You will need to drink more fluids to keep from losing too much fluid.
- Have blood work checked as you have been told by the doctor. Talk with the doctor.
- This drug may affect certain lab tests. Tell all of your health care providers and lab workers that you take this drug.
- It may be harder to control your blood sugar during times of stress like when you have a fever, an infection, an injury, or surgery. A change in level of physical activity or exercise and a change in diet may also affect your blood sugar. Talk with your doctor.
- Check your blood sugar as you have been told by your doctor.
- Too much acid in the blood or urine (ketoacidosis) and very bad urinary tract infections (UTIs) have happened with this drug. Ketoacidosis can be deadly. Both of these health problems may need to be treated in a hospital. Talk with the doctor.
- Talk with your doctor about which glucose tests are best to use.
- Follow the diet and workout plan that your doctor told you about.
- Kidney problems have happened with this drug. Sometimes, kidney problems may need to be treated in the hospital. Dialysis may also be needed. Talk with your doctor.
- It is common to have stomach problems like upset stomach, throwing up, or loose stools (diarrhea) when you start taking this drug. If you have stomach problems later during care, call your doctor right away. This may be a sign of an acid health problem in the blood (lactic acidosis).
- If you are 65 or older, use this drug with care. You could have more side effects.
- There is a chance of pregnancy in women of childbearing age who have not been ovulating. If you want to avoid pregnancy, use birth control that you can trust while taking this drug.
- This drug may cause harm to the unborn baby if you take it while you are pregnant. If you are pregnant or you get pregnant while taking this drug, call your doctor right away.
- You may see something that looks like the tablet in your stool. If this happens, talk with your doctor.
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of dehydration like dry skin, mouth, or eyes; thirst; fast heartbeat; dizziness; fast breathing; or confusion.
- Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
- Signs of too much acid in the blood (acidosis) like confusion; fast breathing; fast heartbeat; a heartbeat the does not feel normal; very bad stomach pain, upset stomach, or throwing up; feeling very sleepy; shortness of breath; or feeling very tired or weak.
- Signs of a urinary tract infection (UTI) like blood in the urine, burning or pain when passing urine, feeling the need to pass urine often or right away, fever, lower stomach pain, or pelvic pain.
- For females, vaginal yeast infection. Report itching or discharge.
- For men, yeast infection of the penis. Report pain, swelling, rash, or discharge.
- Very bad belly pain.
- Very bad dizziness or passing out.
- Low blood sugar can happen. The chance of low blood sugar may be raised when this drug is used with other drugs for high blood sugar (diabetes). Signs may be dizziness, headache, feeling sleepy, feeling weak, shaking, a fast heartbeat, confusion, hunger, or sweating. Call your doctor right away if you have any of these signs. Follow what you have been told to do if you get low blood sugar. This may include taking glucose tablets, liquid glucose, or some fruit juices.
- Nose or throat irritation.
- Stomach pain.
- Feeling tired or weak.
- Take with meals.
- Take with the first meal of the day, if taking once a day.
- Swallow whole. Do not chew, break, or crush.
- If you have trouble swallowing, talk with your doctor.
- Drink lots of noncaffeine liquids after using this drug unless told to drink less liquid by your doctor.
- To gain the most benefit, do not miss doses.
- Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.
- Take a missed dose as soon as you think about it.
- If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
- Do not use 2 doses at the same time or extra doses.
- If you are not sure what to do if you miss a dose, call your doctor.
- Store at room temperature.
- Store in a dry place. Do not store in a bathroom.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- Check with your pharmacist about how to throw out unused drugs.
- If your symptoms or health problems do not get better or if they become worse, call your doctor.
- Do not share your drugs with others and do not take anyone else’s drugs.
- Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
- Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
- Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
- If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.