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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 →

View Alternatives → Compare with Another Drug →

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.

How to Take It

Take Janumet XR once a day with a meal. If you take two tablets, take them together at the same time. Your doctor will adjust your dose based on how well the medicine works for you. Do not crush, split, or chew the tablets.

This is a plain-language summary of metformin/sitagliptin's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.

Pregnancy & Breastfeeding

Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if Janumet XR will harm your unborn baby. Talk to your doctor if you are breastfeeding or plan to breastfeed.

This is a plain-language summary of metformin/sitagliptin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and take your next dose at the regular time.

This is a plain-language summary of metformin/sitagliptin's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.

Storage

Store Janumet XR at room temperature (68-77°F) in a dry place, and keep the cap tightly closed.

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.

What to do: Avoid taking these two medications together. Your doctor or pharmacist should ensure you are only taking one product that contains metformin to prevent an overdose.

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.

What to do: Your healthcare provider may need to check your blood chemistry more often while you take these drugs together.

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.

What to do: Your doctor may need to lower your metformin dose to avoid side effects.

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.

What to do: Your doctor should monitor you closely and might adjust your metformin dosage.

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.

What to do: Your healthcare provider may need to adjust your metformin dose while you are taking cimetidine.

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This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.

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 most commonly reported side effects of metformin/sitagliptin include Diarrhea, Upper respiratory infection, Headache. Based on 164,328 FDA adverse event reports. Always consult your healthcare provider about potential side effects.
Does metformin/sitagliptin interact with other medications?
Yes, metformin/sitagliptin has 7 known drug interactions. Notable interactions include metformin, topiramate, dolutegravir. Always inform your doctor about all medications you are taking.
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.
Is metformin/sitagliptin safe during pregnancy?
Talk to your doctor if you are pregnant or plan to become pregnant. It is not known if Janumet XR will harm your unborn baby. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

Related Medications in Biguanide / DPP-4 Combination

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

acarbose

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bromocriptine

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canagliflozin

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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 further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.

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. Always consult a healthcare professional before making medication decisions.

Last updated: March 25, 2025

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 and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.

All federal data sources used on this page