Short answer: In the label's 24-week trial of linagliptin and metformin started together, the side effects seen in at least 5% and more often than on placebo were stuffy or runny nose with sore throat (6.3% vs 1.4%) and diarrhea (6.3% vs 2.8%). Across three placebo-controlled trials of linagliptin added to metformin, only stuffy or runny nose met that bar (5.7% vs 4.3%). Jentadueto has a boxed warning for lactic acidosis from its metformin part.
What Jentadueto is approved for: Jentadueto combines linagliptin, a DPP-4 inhibitor, with metformin, a biguanide. It is approved, along with diet and exercise, to improve blood sugar control in adults with type 2 diabetes (section 1). It is not recommended in type 1 diabetes, and it has not been studied in people who have had pancreatitis.
Source
JENTADUETO (linagliptin and metformin hydrochloride tablets), for oral use, prescribing information and Medication Guide. Boehringer Ingelheim Pharmaceuticals. DailyMed, version published August 26, 2026. DailyMed setid f6dd9b86-0d18-95d4-2bc7-05591bfdd597
WARNING: LACTIC ACIDOSIS
Cases of metformin-associated lactic acidosis reported after approval have resulted in death, low body temperature, low blood pressure and slow heart rhythms that resist treatment. It often starts subtly, with only vague symptoms such as feeling unwell, muscle aches, trouble breathing, sleepiness and abdominal pain. It was marked by blood lactate above 5 mmol/L, anion gap acidosis without ketones, a raised lactate to pyruvate ratio, and metformin levels generally above 5 mcg/mL. Risk factors include kidney impairment, certain drugs (for example carbonic anhydrase inhibitors such as topiramate), age 65 or older, a radiology study with contrast, surgery and other procedures, low-oxygen states such as acute heart failure, heavy alcohol use, liver impairment and mitochondrial diseases. If it is suspected, Jentadueto is stopped immediately and supportive care is started in a hospital; prompt hemodialysis is recommended.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Jentadueto.
| Adverse reaction | Placebo (%) n=72 | Linagliptin Monotherapy (%) n=142 | Metformin Monotherapy (%) n=291 | Combination of Linagliptin with Metformin (%) n=286 |
|---|---|---|---|---|
| Nasopharyngitis | 1.4 | 5.6 | 2.7 | 6.3 |
| Diarrhea | 2.8 | 3.5 | 3.8 | 6.3 |
Percent of patients. Nasopharyngitis means a stuffy or runny nose with sore throat.
In three placebo-controlled trials of linagliptin added to metformin (875 vs 539 people), the only side effect in at least 5% and more common than placebo was stuffy or runny nose with sore throat: 5.7% vs 4.3%.
Other side effects reported with linagliptin plus metformin: allergic reactions (such as hives, angioedema or airway tightening), cough, decreased appetite, nausea, vomiting, itching and pancreatitis.
Low blood sugar in the 24-week factorial trial: 1.4% on linagliptin plus metformin, 2.1% on metformin and 1.4% on placebo. With metformin and a sulfonylurea, blood sugar below 54 mg/dL was 8.1% on linagliptin vs 5.3% on placebo. With basal insulin for 52 weeks, severe low blood sugar was 1.7% vs 1.1%.
Linagliptin 5 mg vs placebo: stuffy or runny nose 7.0% vs 6.1%, diarrhea 3.3% vs 3.0%, and cough 2.1% vs 1.4%. Pancreatitis in the linagliptin program was 15.2 cases per 10,000 patient-years vs 3.7 on comparator, plus three cases after the last dose.
Metformin: the most common side effects when starting it are diarrhea, nausea or vomiting, gas, abdominal discomfort, indigestion, weakness and headache. In metformin trials of 29 weeks, vitamin B12 fell below normal in about 7%.
Reported after approval, with frequency unknown: acute pancreatitis including fatal cases; mouth ulcers; allergic reactions including anaphylaxis, angioedema and skin peeling; rhabdomyolysis; severe joint pain; bullous pemphigoid; rash; and, for metformin, liver injury.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Lactic acidosis. The boxed-warning risk. Jentadueto is not used with an eGFR below 30, and starting it at 30 to 45 is not recommended. eGFR is checked before starting and at least yearly, more often in older people. It is stopped around some iodinated contrast scans, paused while food and fluids are restricted, stopped in shock, heart attack, sepsis or acute heart failure with low oxygen, avoided with liver disease, and not recommended with mitochondrial diseases such as MELAS and MIDD.
Pancreatitis. Acute pancreatitis, including fatal cases, has been reported with linagliptin. In the CARMELINA trial it was 0.3% on linagliptin vs 0.1% on placebo, with two deaths on linagliptin. Jentadueto is stopped promptly if it is suspected.
Low blood sugar with insulin or a sulfonylurea. Low blood sugar risk rises with insulin or a medicine that makes the body release insulin, so a lower dose of those may be needed.
Hypersensitivity reactions. Serious allergic reactions to linagliptin, including anaphylaxis, angioedema and skin peeling conditions, have been reported, mostly within the first 3 months and some after the first dose. Jentadueto is stopped if one is suspected.
Vitamin B12 deficiency. Metformin may lower vitamin B12. Blood counts are measured yearly and vitamin B12 every 2 to 3 years.
Severe and disabling joint pain. Severe joint pain has been reported with linagliptin, starting from one day to years after starting, and easing after stopping.
Bullous pemphigoid. A blistering skin condition was reported in 0.2% on linagliptin vs none on placebo in CARMELINA. Jentadueto is stopped if it is suspected.
Heart failure. Heart failure was linked to two other DPP-4 inhibitors. Risks and benefits are weighed in people at risk, and they are watched for symptoms.
From the Medication Guide that comes with Jentadueto:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.