- 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. The risk is also higher in people who are having an exam or test with contrast, surgery, or other procedures. 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. If you have questions, 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 (dehydration).
- If you have liver disease, talk with your doctor.
- 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).
- 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, bladder cancer, 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 breast-feeding or plan to breast-feed.
- Avoid driving and doing other tasks or actions that call for you to be alert until you see how this drug affects you.
- 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 if you have been sitting or lying down. Be careful going up and down 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.
- Bladder cancer has happened in a few more people taking this drug than in those taking other drugs for diabetes. It is not known if this drug led to these cases of bladder cancer. Talk with 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.
- 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).
- Follow the diet and workout plan that your doctor told you about.
- If you are on a low-salt or salt-free diet, talk with your doctor.
- If you are 65 or older, use this drug with care. You could have more side effects.
- Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this drug while you are pregnant.
- You may see something that looks like the tablet in your stool. This is normal and not a cause for concern. If you have questions, 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, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of fluid and electrolyte problems like mood changes, confusion, muscle pain or weakness, a heartbeat that does not feel normal, very bad dizziness or passing out, fast heartbeat, more thirst, seizures, feeling very tired or weak, not hungry, unable to pass urine or change in the amount of urine produced, dry mouth, dry eyes, or very bad upset stomach or throwing up.
- 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.
- 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.
- Loose stools (diarrhea).
- Upset stomach or throwing up.
- Nose or throat irritation.
- Take this drug with food.
- Drink lots of noncaffeine liquids 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 in the morning.
- Swallow whole. Do not chew, break, or crush.
- Skip the missed dose and go back to your normal time.
- Do not take 2 doses at the same time or extra doses.
- 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 take 2 doses at the same time or extra doses unless told to do so by 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.
- Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
- 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.