Janumet

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Jul 22, 2022

Warnings

Janumet Risks, Warnings, and Complications

Janumet can cause serious health problems, especially in certain high-risk patients. Some of the risks of Janumet therapy include:

METFORMIN-ASSOCIATED LACTIC ACIDOSIS: Janumet contains a medication called metformin. Very rarely, metformin accumulation in patients treated with Janumet can lead to a condition called lactic acidosis, in which there are abnormally high levels of lactic acid in the blood. This is a potentially lethal condition and is a medical emergency.
Give your doctor a complete medical history and tell them about any existing health problems before starting Janumet (sitagliptin and metformin) therapy.
Discontinue Janumet XR or Janumet and call your healthcare provider immediately if you experience signs and symptoms of lactic acidosis, such as fast breathing, slow or fast heartbeat, abnormal heartbeat, shortness of breath, vomiting, upset stomach, sleepiness, tiredness, weakness, dizziness, muscle pain, or feeling cold.
The risk of lactic acidosis in metformin-treated patients is higher if there is existing significant renal impairment or hepatic impairment (kidney disease or liver disease), heart problems, excessive alcohol intake, age over 65 years, and the use of contrast dye for imaging studies.
Taking certain drugs with metformin also increases the risk of lactic acidosis, such as acetazolamide (Diamox), methazolamide, dichlorphenamide (Keveyis), zonisamide (Zonegran), and topiramate (Topamax, in Qsymia).
HEART FAILURE: Controlled clinical trials have shown a possible link between DPP-4 inhibitors like sitagliptin and heart failure. Patients treated with Janumet should be vigilant for heart failure symptoms such as shortness of breath, irregular or rapid heartbeat, chest pain, fluid retention, and weight gain. The risk is higher in people with existing heart failure and those with kidney problems. You should contact your doctor without delay if you notice any symptoms of heart failure while taking Janumet.
LOW VITAMIN B12: Long-term metformin treatment can cause low vitamin B12 levels and anemia. Contact your doctor if you have low energy, muscle weakness, reduced appetite, or numbness or tingling in the hands or feet. Your doctor may order a blood test to check your vitamin B12 levels every couple of years.
JOINT PAIN: The sitagliptin in Janumet is a DPP-4 inhibitor and can cause severe and disabling joint pain. This can happen within days of starting the medicine or years later. Contact your doctor right away if you experience any joint pain or discomfort.
HYPOGLYCEMIA: Patients inadequately controlled on one medication may be given other diabetes medications along with Janumet (sitagliptin and metformin). Janumet alone or in combination with other medications can lead to hypoglycemia (dangerously low blood sugar levels) that can be life-threatening.
Signs and symptoms of low blood sugar include shakiness, nervousness, anxiety, fast heartbeat, chills or sweating, sleepiness, confusion, low energy, weakness, and excessive hunger.
Talk to your doctor about what to do if you experience symptoms of hypoglycemia (low blood sugar). Risk factors for hypoglycemia include taking other diabetes medications, major changes in diet and exercise, severe infection, excessive alcohol intake, age over 65 years, and liver and kidney problems

If you are at a high risk of complications from Janumet use, discuss dose adjustment or alternative treatments with your doctor or pharmacist.

Precautions Before Starting Janumet

Tell your healthcare provider if you have ever had an allergic reaction to sitagliptin or metformin, any active or inactive ingredients in Janumet tablets, or any other medications. Your pharmacy can give you a list of ingredients.

Give your healthcare provider a complete medical history. Janumet may not be right for people with certain medical conditions such as chronic or acute pancreatitis, severe renal impairment (kidney disease), heart failure, gallstones, or high triglycerides. Also, tell your doctor if you have ever had diabetic ketoacidosis and if you have excessive alcohol intake.

Give your doctor a complete list of all your medications, including prescription drugs, over-the-counter medicines, vitamins, dietary supplements, and herbal products. This can help avoid serious drug interactions between Janumet (sitagliptin and metformin) and other drugs.

Tell your doctor if you are pregnant, could be pregnant, plan to get pregnant, or are breastfeeding.

Talk with your doctor about the symptoms of high blood sugar and low blood sugar and what to do should they occur.

Precautions During Use of Janumet

Keep all your medical and lab appointments while on Janumet. Your doctor may want to check how well the medication works to improve glycemic control (blood sugar levels). Your provider may order certain laboratory tests to assess renal function and vitamin B12 levels during treatment with this medication. This will allow your doctor to identify any worsening renal function as soon as possible.

Tell your doctor if there are any big changes in your diet, exercise levels, or weight; if you become dehydrated or if you are eating or drinking less due to an illness that causes nausea, vomiting, and diarrhea; or if you are undergoing surgery, have a severe infection and/or fever, are experiencing unusual stress, or have suffered an injury. These conditions can lead to fluctuations in blood sugar levels and may affect the amount of Janumet you need.

Tell your health care professionals you are on Janumet before undergoing any surgery, including dental surgery.

Call your doctor if you become pregnant while on Janumet. This medication can pass into breast milk. Do not breastfeed while on Janumet.

Janumet Drug Interactions

Taking Janumet together with certain drugs can affect how the medications work. Interactions between medications can also increase the risk of serious adverse reactions. Your physician may choose different diabetes medications for you, change the dose or frequency of one or both medicines, and/or closely monitor you for side effects if there are known interactions between Janumet and your other medications.

There can be potential interactions between Janumet and the following medications:

Insulin therapy
Other oral diabetes medications
Diuretics or water pills
Medications used to treat high blood pressure and heart problems including angiotensin-converting enzyme (ACE) inhibitors, beta-blockers, and calcium channel blockers
Heart medications like digoxin (Lanoxicaps, Lanoxin), procainamide, and quinidine (in Nuedexta)
Hormone replacement therapy
Oral contraceptives
Cimetidine (Tagamet)
Ranitidine (Zantac)
Asthma and cold medications
Psychiatric medications
Thyroid medications
Pain medications like morphine (MS Contin, others)
Oral steroids
Anti-seizure medications like phenytoin (Dilantin, Phenytek)
Malaria drugs like quinine
Antibiotics like trimethoprim (Primsol) and vancomycin (Vancocin)
Isoniazid (Laniazid, in Rifamate, in Rifater)

This list does not describe all possible Janumet interactions. Give your healthcare professionals a complete list of your medications, including prescription drugs, over-the-counter medicines, vitamins, dietary supplements, and herbal products. Also, tell your health care provider if you smoke, drink alcohol, or use illegal drugs because some of these substances can cause serious health complications when used with prescription drugs.

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