Prescription medication · Biguanide / DPP-4 Combination

metformin/sitagliptin

Also sold as Janumet. Janumet XR is used to help control blood sugar levels in adults who have type 2 diabetes.

Data updated 2026-05-15

164,328
FDA reports
7
InteractionsFew interactions
$9.17
Brand price (NADAC)

What the data shows

metformin/sitagliptin (Janumet) is a prescription Biguanide / DPP-4 Combination, with 164,328 FDA adverse-event reports on file, with 7 documented drug interactions.

Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.

metformin/sitagliptin (Janumet) is a prescription Biguanide / DPP-4 Combination. Janumet XR is used to help control blood sugar levels in adults who have type 2 diabetes.

Janumet XR is a drug that combines sitagliptin and metformin. It helps lower blood sugar in adults with type 2 diabetes, along with diet and exercise.

Verify with FDA → · CMS NADAC pricing →

Drug Pricing (NADAC)

Brand Price

$9.17/unit

Generic Available

No

Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →

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What it does

Janumet XR is used to help control blood sugar levels in adults who have type 2 diabetes.

Common side effects

Diarrhea, Upper respiratory infection, Headache

Key warnings

Metformin can cause a rare but serious side effect called lactic acidosis.

The sections below are summarized in plain English from metformin/sitagliptin's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

How It Works

Janumet XR contains two medicines. Sitagliptin helps your body release more insulin after you eat. Metformin helps your body use insulin better and reduces sugar production in the liver.

Side Effects (from patient reports)

Based on 164,328 FDA adverse event reports.

Most-reported reactions

Adverse reactions in FAERS for metformin/sitagliptin, by number of reports

reports

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Source FDA Adverse Event Reporting System (FAERS)

Serious Warnings

Metformin can cause a rare but serious side effect called lactic acidosis. Get medical help right away if you have symptoms like feeling very weak, muscle pain, trouble breathing, stomach pain, dizziness, or a slow or irregular heartbeat. Certain conditions increase your risk, such as kidney problems, drinking too much alcohol, or having surgery.

Known Drug Interactions

moderate metformin

Drug Interactions The concomitant use of JANUMET XR with specific drugs may increase the risk of metformin-associated lactic acidosis: those that impair renal function, result in significant hemodynamic change, interfere with acid-base balance or increase metformin accumulation [see Drug Interactions (7) ]. Drugs that Reduce Metformin Clearance Clinical Impact: Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT 2 ] / multidrug and toxin extrusion [MATE] inhibitors)...

Mechanism: Both of these medications contain metformin, so taking them together results in a double dose of the same ingredient. This significantly increases the risk of a dangerous buildup of acid in your bloodstream.

minor topiramate

Examples: Topiramate, zonisamide, acetazolamide or dichlorphenamide.

Mechanism: Topiramate changes how your body handles acid in the blood, which can increase the risk of side effects from metformin.

minor dolutegravir

Examples: Ranolazine, vandetanib, dolutegravir, and cimetidine. ( 7 ) Drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) may increase the accumulation of metformin.

Mechanism: Dolutegravir slows down the process of removing metformin from your body, which can cause the drug to build up to high levels.

minor ranolazine

Examples: Ranolazine, vandetanib, dolutegravir, and cimetidine. ( 7 ) Drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) may increase the accumulation of metformin.

Mechanism: Ranolazine makes it harder for your kidneys to clear metformin out of your system, leading to higher amounts of the drug in your blood.

minor cimetidine

Examples: Ranolazine, vandetanib, dolutegravir, and cimetidine. ( 7 ) Drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) may increase the accumulation of metformin.

Mechanism: Cimetidine blocks the way your body gets rid of metformin, which can cause metformin to reach unsafe levels in your body.

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This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.

Common Questions

What should I do if I experience severe joint pain while taking Janumet XR?
Tell your doctor right away if you have severe joint pain. They may want to stop the medicine.
Can Janumet XR be used to treat type 1 diabetes?
No, Janumet XR is only for type 2 diabetes.
What should I do before having an X-ray or CT scan with contrast dye?
Tell your doctor you are taking Janumet XR. You may need to stop taking it temporarily.
Does Janumet XR cause weight gain?
Weight gain is not a common side effect of Janumet XR. Some people may even lose weight.
Can I drink alcohol while taking Janumet XR?
You should avoid drinking too much alcohol while taking Janumet XR because it can increase your risk of lactic acidosis.
What happens if my kidney function gets worse while taking Janumet XR?
Your doctor will check your kidney function regularly. If it gets worse, your doctor may need to lower your dose or stop the medicine.
Can Janumet XR cause low blood sugar?
Janumet XR can cause low blood sugar, especially if you are also taking insulin or other diabetes medicines. Talk to your doctor about how to prevent and treat low blood sugar.
How often will my doctor check my kidney function?
Your doctor will check your kidney function before you start Janumet XR and at least once a year after that.
What are the symptoms of lactic acidosis?
Symptoms include feeling very weak, muscle pain, trouble breathing, stomach pain, dizziness, or a slow or irregular heartbeat.
Can I cut the Janumet XR tablet in half?
No, do not split, crush, or chew Janumet XR tablets. Swallow them whole.
What are the common side effects of metformin/sitagliptin?
The registry lists Diarrhea, Upper respiratory infection, Headache among the most-reported FAERS reaction terms for metformin/sitagliptin. The compiled record contains 164,328 FDA adverse-event reports. These counts are not an individual symptom assessment.
Does metformin/sitagliptin interact with other medications?
The registry has 7 documented interaction rows for metformin/sitagliptin. Notable source-record pairings include metformin, topiramate, dolutegravir. These rows are not a complete medication review.
What drug class is metformin/sitagliptin?
metformin/sitagliptin belongs to the Biguanide / DPP-4 Combination drug class. It requires a prescription (Rx). Janumet XR is used to help control blood sugar levels in adults who have type 2 diabetes.
What pregnancy or breastfeeding source fields are listed for metformin/sitagliptin?
The FDA label for metformin/sitagliptin contains product-specific pregnancy or breastfeeding language. PlainMeds does not apply that source text to an individual.

Related Medications in Biguanide / DPP-4 Combination

Other drugs grouped near metformin/sitagliptin - same-class peers and common alternatives.

acarbose

Precose

Acarbose is a medicine that helps lower blood sugar levels in people with type 2 diabetes.

Compare with metformin/sitagliptin →

alogliptin

Nesina

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bromocriptine

Cycloset

Bromocriptine (Cycloset) is a medicine that acts like dopamine in your body.

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canagliflozin

Invokana

Invokana is a medicine used with diet and exercise to lower blood sugar in adults with type 2 diabetes.

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colesevelam

Welchol

Colesevelam is a medicine that helps lower bad cholesterol (LDL-C) and control blood sugar in adults.

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Compare metformin/sitagliptin vs acarbose side-by-side →

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What the FDA Data Shows for metformin/sitagliptin

The FDA label for metformin/sitagliptin (sold under brand names such as Janumet) classifies it as a prescription-only medication in the Biguanide / DPP-4 Combination class. Janumet XR is used to help control blood sugar levels in adults who have type 2 diabetes. Official labeling lists 3 commonly reported side effects, including Diarrhea, Upper respiratory infection, Headache.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 164,328 voluntary reports. The database also lists 7 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS.

Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.

Last updated: March 25, 2025

PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.

Read our methodology - how this data is sourced, computed, and verified.

Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.

All federal data sources used on this page