Serious side effects can happen in people taking Janumet, including:

1. Lactic Acidosis. Metformin, one of the medicines in Janumet, can cause a rare but serious condition called lactic acidosis (a build-up of lactic acid in the blood) that can cause death. Lactic acidosis is a medical emergency and must be treated in the hospital.

Stop taking Janumet and call your doctor right away if you get any of the following symptoms, which could be signs of lactic acidosis.

You:

• feel very weak or tired.
• have unusual (not normal) muscle pain.
• have trouble breathing.
• have unusual sleepiness or sleep longer than usual.
• have sudden stomach or intestinal problems with nausea and vomiting or diarrhea.
• feel cold, especially in your arms and legs.
• feel dizzy or lightheaded.
• have a slow or irregular heartbeat.

You have a higher chance of getting lactic acidosis if you:

• have kidney problems. People whose kidneys are not working properly should not take Janumet.
• have liver problems.
• have congestive heart failure that requires treatment with medicines.
• drink alcohol very often, or drink a lot of alcohol in short-term "binge" drinking.
• get dehydrated (lose a large amount of body fluids). This can happen if you are sick with a fever, vomiting, or diarrhea. Dehydration can also happen when you sweat a lot with activity or exercise and do not drink enough fluids.
• have certain x-ray tests with dyes or contrast agents that are injected into your body.
• have surgery.
• have a heart attack, severe infection, or stroke.
• are 80 years of age or older and have not had your kidneys tested.

2. Pancreatitis (inflammation of the pancreas) which may be severe and lead to death.

Certain medical problems make you more likely to get pancreatitis.

Before you start taking Janumet:

Tell your doctor if you have ever had

• pancreatitis
• stones in your gallbladder (gallstones)
• a history of alcoholism
• high blood triglyceride levels

Stop taking Janumet 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.

Do not take Janumet if you are allergic to any of the ingredients in Janumet.

Symptoms of a serious allergic reaction to Janumet may include:

• rash
• raised red patches on your skin (hives)
• swelling of the face, lips, tongue, and throat that may cause difficulty in breathing or swallowing

Tell your doctor if:

• you have kidneys which are not working properly.
• you are going to get an injection of dye or contrast agents for an x-ray procedure, Janumet will need to be stopped for a short time. Talk to your doctor about when you should stop Janumet and when you should start Janumet again.