Metformin, one of the medicines in JANUMET and JANUMET XR, can cause a rare but serious side effect called lactic acidosis (a buildup of lactic acid in the blood), which can cause death. Lactic acidosis is a medical emergency that must be treated in a hospital. Stop taking JANUMET or JANUMET XR and call your doctor right away if you get any of the following symptoms, which could be signs of lactic acidosis: feel cold in your hands or feet; feel dizzy or lightheaded; have a slow or irregular heartbeat; feel very weak or tired; have unusual (not normal) muscle pain; have trouble breathing; feel sleepy or drowsy; have stomach pains, nausea, or vomiting.
Most people who have had lactic acidosis with metformin have other things that, combined with the metformin, led to the lactic acidosis. Tell your doctor if you have any of the following, because you have a higher chance of getting lactic acidosis with JANUMET or JANUMET XR if you: have severe kidney problems or your kidneys are affected by certain x-ray tests that use injectable dye; have liver problems; drink alcohol very often, or drink a lot of alcohol in short-term “binge” drinking; get dehydrated (lose large amounts of body fluids, which may happen if you are sick with fever, vomiting, or diarrhea; if you sweat a lot with activity or exercise and do not drink enough fluids); have surgery; have a heart attack, severe infection, stroke, or are 65 years of age or older. Your doctor may decide to stop your JANUMET or JANUMET XR for a while if you have any of these things.
Pancreatitis (inflammation of the pancreas) is another serious side effect that can happen in people taking JANUMET or JANUMET XR. Pancreatitis may be severe and lead to death. Certain medical problems make you more likely to get pancreatitis. Before you start taking JANUMET or JANUMET XR, tell your doctor if you’ve ever had pancreatitis. Stop taking JANUMET or JANUMET XR and call your doctor right away if you have pain in your stomach area (abdomen) that is severe and will not go away. The pain may be felt going from your abdomen through to your back. The pain may happen with or without vomiting. These may be symptoms of pancreatitis.
Before you start taking JANUMET or JANUMET XR, tell your doctor if you have ever had heart failure (your heart does not pump blood well enough) or have problems with your kidneys. Contact your doctor right away if you have increasing shortness of breath or trouble breathing (especially when you lie down); swelling or fluid retention (especially in the feet, ankles, or legs); an unusually fast increase in weight; or unusual tiredness. These may be symptoms of heart failure.
Do not take JANUMET or JANUMET XR if you have severe kidney problems or have diabetic ketoacidosis. Your doctor will do blood tests before and during your treatment to see how well your kidneys are working.
Do not take JANUMET or JANUMET XR if you are allergic to any of the ingredients in JANUMET or JANUMET XR. Allergic reactions, which may be serious, including rash; hives; or swelling of the face, lips, tongue, and throat that may cause difficulty breathing or swallowing, can occur. If you have an allergic reaction, stop taking JANUMET or JANUMET XR and call your doctor right away or get emergency medical help.
Tell your doctor if you are going to get an injection of dye or contrast agent for an x-ray procedure; JANUMET or JANUMET XR may need to be stopped for a short time.
Kidney problems, sometimes requiring dialysis, have been reported.
Low vitamin B12 (vitamin B12 deficiency). Using metformin for long periods of time may cause a decrease in the amount of vitamin B12 in your blood, especially if you have had low vitamin B12 blood levels before. Your doctor may do blood tests to check your vitamin B12 levels.
If you take JANUMET or JANUMET XR with another medicine that can cause low blood sugar (hypoglycemia), such as a sulfonylurea or insulin, your risk of getting low blood sugar is higher. The dose of your sulfonylurea or insulin may need to be lowered. Signs and symptoms of low blood sugar may include headache, drowsiness, irritability, hunger, dizziness, confusion, sweating, feeling jittery, weakness, and fast heartbeat.
Some people who take medicines called DPP-4 inhibitors, one of the medicines in JANUMET and JANUMET XR, may develop joint pain that can be severe. Call your doctor if you have severe joint pain.
Some people who take medicines called DPP-4 inhibitors, one of the medicines in JANUMET and JANUMET XR, may develop a skin reaction called bullous pemphigoid that can require treatment in a hospital. Tell your doctor right away if you develop blisters or the breakdown of the outer layer of your skin (erosion). Your doctor may tell you to stop taking JANUMET or JANUMET XR.
Common side effects when taking JANUMET or JANUMET XR include stuffy or runny nose and sore throat, gas, upset stomach, indigestion, headache, upper respiratory tract infection, weakness, diarrhea, low blood sugar (hypoglycemia) when used in combination with certain medicines such as sulfonylurea or insulin, nausea and vomiting.
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.
Please read the accompanying Medication Guide for JANUMET (sitagliptin and metformin HCl) tablets or JANUMET XR (sitagliptin and metformin HCl extended-release) tablets, including the information about lactic acidosis, and discuss it with your doctor. The physician Prescribing Information for JANUMET or JANUMET XR also is available.
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