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Janumet XR Side Effects

Generic name: metformin / sitagliptin

Medically reviewed by Last updated on Dec 21, 2023.

Note: This document contains side effect information about metformin / sitagliptin. Some dosage forms listed on this page may not apply to the brand name Janumet XR.

Applies to metformin / sitagliptin: oral tablet, oral tablet extended release.


Oral route (Tablet; Tablet, Extended Release)

Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, an increased lactate/pyruvate ratio, and metformin plasma levels generally greater than 5 mcg/mL. Risk factors include renal impairment, concomitant use of certain drugs (eg, carbonic anhydrase inhibitors), age 65 years old or greater, radiological studies with contrast, surgery and other procedures, hypoxic states, excessive alcohol intake, and hepatic impairment. If lactic acidosis is suspected, immediately discontinue metformin hydrochloride/sitagliptin phosphate and institute general supportive measures in a hospital setting; prompt hemodialysis is recommended.

Serious side effects of Janumet XR

Along with its needed effects, metformin / sitagliptin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking metformin / sitagliptin:

Less common


Incidence not known

Other side effects of Janumet XR

Some side effects of metformin / sitagliptin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

For Healthcare Professionals

Applies to metformin / sitagliptin: oral tablet, oral tablet extended release.



Very common (10% or more): Hypoglycemia (13.8% when combined with sulfonylurea; 10.9% when combined with insulin)

Common (1% to 10%): Hypoglycemia, decrease levels of vitamin B12 without clinical manifestations and rarely associated with anemia

Rare (less than 0.1%): Lactic acidosis due to metformin


Uncommon (0.1% to 1%): Hypoglycemia


Common (1% to 10%): Hypoglycemia (5% or more when combined with glyburide)

Uncommon (0.1% to 1%): Hypoglycemia

Very rare (less than 0.01%): Lactic acidosis, vitamin B12 deficiency[Ref]

In metformin-treated patients, the incidence of lactic acidosis has been about 1.5 cases per 10,000 patient years. The risk of lactic acidosis has been particularly high in patients with underlying renal insufficiency and rarely in patients with normal renal function. Concomitant cardiovascular or liver disease, sepsis, and hypoxia have also increased the risk of lactic acidosis.

Signs and symptoms of severe acidosis may include vomiting, abdominal pain, nausea, dyspnea, hypothermia, hypotension, and bradycardia.

Long-term treatment with metformin has been associated with a decrease in vitamin B12 absorption. Malabsorption of vitamin B12, due to intrinsic factor deficiency and possibly other mechanisms, in as many as 30% of treated patients, were reported. Megaloblastic anemia has occurred. Decreased levels of vitamin B12 appear to be reversible with discontinuation of metformin or vitamin B12 supplementation.[Ref]


Common (1% to 10%): Diarrhea, nausea, flatulence, vomiting

Uncommon (0.1% to 1%): Constipation, upper abdominal pain, dry mouth

Postmarketing reports: Indigestion, abdominal discomfort, dyspepsia, abdominal pain, acute pancreatitis (including fatal and non-fatal hemorrhagic and necrotizing pancreatitis), mouth ulceration, stomatitis


Very common (10% or more): Nausea, vomiting, diarrhea, abdominal pain, loss of appetite


Rare (less than 0.1%): Pancreatitis[Ref]

Nervous system


Common (1% to 10%): Headache

Uncommon (0.1% to 1%): Somnolence

Frequency not reported: Asthenia


Common (1% to 10%): metallic taste[Ref]


Common (1% to 10%): Upper respiratory tract infections, nasopharyngitis, pharyngolaryngeal pain, bronchitis, sinusitis, influenza

Postmarketing reports: Interstitial lung disease[Ref]


Frequency not reported: Hypersensitivity reactions including anaphylaxis[Ref]



Postmarketing reports: Hepatic enzyme elevation


Very rare (less than 0.01%): Liver function disorders, hepatitis


Frequency not reported: Impaired renal function, acute renal failure (sometimes requiring dialysis)


Common (1% to 10%): Arthralgia

Postmarketing reports: Myalgia, pain in extremities, back pain, rhabdomyolysis[Ref]

Between October 2006 and December 2013, thirty-three cases of severe arthralgia have been reported to the FDA Adverse Event Reporting System Database. Each case involved the use of 1 or more dipeptidyl peptidase-4 (DPP-4) inhibitor. In all cases, substantial reduction in prior activity level was reported, 10 patients were hospitalized due to disabling joint pain. In 22 cases, symptoms appeared within 1 month of starting therapy, in 23 cases symptoms resolved less than 1 month after discontinuation. A positive rechallenge was reported in 8 cases, with 6 cases involving use of a different DPP-4 inhibitor. Sitagliptin had the greatest number of cases reported (n=28) followed by saxagliptin (n=5), linagliptin (n=2), alogliptin (n=1), and vildagliptin (n=2).[Ref]


Common (1% to 10%): Peripheral edema


Postmarketing reports: Angioedema, rash, urticaria, pruritus, cutaneous vasculitis, exfoliative skin conditions including Steven-Johnson syndrome


Very rare (less than 0.01%): Urticaria, erythema, pruritus


Rare (less than 0.1%): Megaloblastic anemia[Ref]

Decreased serum vitamin B12 levels, without clinical manifestations (rarely megaloblastic anemia), has been reported in approximately 7% of patients. The reduction in vitamin B12 levels may be due to interference with B12 absorption from the B12-intrinsic factor complex and appears to be rapidly reversible with discontinuation of metformin or vitamin B12 supplementation.[Ref]


1. (2007) "Product Information. Janumet (metformin-sitagliptin)." Merck & Co., Inc

2. US Food and Drug Administration (2015) FDA Drug Safety Communication: FDA warns that DPP-4 inhibitors for type 2 diabetes may cause severe joint pain.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.