Short answer: The label says side effects in the trials of ertugliflozin added to metformin were similar to its pooled ertugliflozin table. There, the most common were female genital yeast infections (9.1% on 5 mg and 12.2% on 15 mg vs 3.0% on placebo), male genital yeast infections (3.7% and 4.2% vs 0.4%) and urinary tract infections (4.0% and 4.1% vs 3.9%). Segluromet has a boxed warning for lactic acidosis from its metformin part.
What Segluromet is approved for: Segluromet combines ertugliflozin, an SGLT2 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 for type 1 diabetes.
Source
SEGLUROMET (ertugliflozin and metformin hydrochloride) tablets, for oral use, prescribing information and Medication Guide. Merck Sharp & Dohme. DailyMed, version published August 28, 2026. DailyMed setid a6aeb99a-ce49-4125-90ce-642df3f1ebad
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, Segluromet 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 Segluromet.
| Adverse reaction | Placebo N = 515 | Ertugliflozin 5 mg N = 519 | Ertugliflozin 15 mg N = 510 |
|---|---|---|---|
| Female genital mycotic infections | 3.0% | 9.1% | 12.2% |
| Male genital mycotic infections | 0.4% | 3.7% | 4.2% |
| Urinary tract infections | 3.9% | 4.0% | 4.1% |
| Headache | 2.3% | 3.5% | 2.9% |
| Vaginal pruritus | 0.4% | 2.8% | 2.4% |
| Increased urination | 1.0% | 2.7% | 2.4% |
| Nasopharyngitis | 2.3% | 2.5% | 2.0% |
| Back pain | 2.3% | 1.7% | 2.5% |
| Weight decreased | 1.0% | 1.2% | 2.4% |
| Thirst | 0.6% | 2.7% | 1.4% |
Number (%) of patients in a pool of three 26-week placebo-controlled trials: one of ertugliflozin alone and two added to metformin or to metformin and sitagliptin. Female and male rates use the number of women or men in each group. Nasopharyngitis means a stuffy or runny nose with sore throat.
| Study and measure | Placebo | Ertugliflozin 5 mg | Ertugliflozin 15 mg |
|---|---|---|---|
| Add-on to metformin HCl, 26 weeks (N = 209 / 207 / 205): Overall [N (%)] | 9 (4.3) | 15 (7.2) | 16 (7.8) |
| Add-on to metformin HCl: Severe [N (%)] | 1 (0.5) | 1 (0.5) | 0 (0.0) |
| Add-on to metformin HCl and sitagliptin, 26 weeks (N = 153 / 156 / 153): Overall [N (%)] | 5 (3.3) | 7 (4.5) | 3 (2.0) |
| Add-on to metformin HCl and sitagliptin: Severe [N (%)] | 1 (0.7) | 1 (0.6) | 0 (0.0) |
| Add-on to insulin with or without metformin HCl, 18 weeks (N = 347 / 348 / 370): Overall [N (%)] | 130 (37.5) | 137 (39.4) | 144 (38.9) |
| Add-on to insulin with or without metformin HCl: Severe [N (%)] | 12 (3.5) | 13 (3.7) | 19 (5.1) |
| Add-on to metformin HCl and a sulfonylurea, 18 weeks (N = 117 / 100 / 113): Overall [N (%)] | 17 (14.5) | 20 (20.0) | 30 (26.5) |
| Add-on to metformin HCl and a sulfonylurea: Severe [N (%)] | 1 (0.9) | 2 (2.0) | 2 (1.8) |
Overall means a glucose of 70 mg/dL or less; severe means needing help, losing consciousness or having a seizure, whatever the glucose.
Metformin: the most common side effects when starting it (5% or more) are diarrhea, nausea, vomiting, gas, abdominal discomfort, indigestion, weakness and headache. In metformin trials of 29 weeks, vitamin B12 fell below normal in about 7%.
In people with moderate kidney impairment, fluid-loss side effects such as dehydration, dizziness on standing, fainting and low blood pressure were 0% on placebo, 4.4% on ertugliflozin 5 mg and 1.9% on 15 mg.
In the VERTIS CV heart outcome trial, lower limb amputations were 4.7, 5.7 and 6.0 events per 1,000 patient-years on placebo, ertugliflozin 5 mg and 15 mg; urinary tract infections were 10.2%, 12.2% and 12.0%.
Phimosis (tight foreskin) was reported in 8 of 1,729 men (0.5%) on ertugliflozin, four of whom needed circumcision. LDL cholesterol rose 2.6% on 5 mg and 5.4% on 15 mg relative to placebo at week 26.
Reported after approval, with frequency unknown: Fournier's gangrene; angioedema and 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. Segluromet is not recommended with an eGFR below 45 and is not used below 30, in end-stage kidney disease or on dialysis. eGFR is checked before starting and at least yearly. 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.
Diabetic ketoacidosis in type 1 diabetes and other ketoacidosis. Ketoacidosis, which can be fatal, can happen even with blood sugar below 250 mg/dL, and has been reported in type 2 diabetes. Sugar keeps showing in the urine for 4 days after stopping. Segluromet is stopped if ketoacidosis is suspected, and it is not for type 1 diabetes.
Lower limb amputation. In a heart outcome trial, amputations were more frequent on ertugliflozin, mostly of the toe and foot. People are watched for infections, new pain, sores or ulcers of the legs and feet.
Volume depletion. Segluromet can cause fluid loss, low blood pressure and acute kidney injury, especially with kidney problems, in older people, with low blood pressure or with loop diuretics. Fluid status and kidney function are checked before starting.
Genitourinary infections, including Fournier's gangrene. Serious urinary infections, kidney infections, genital yeast infections and a rare, life-threatening genital-area infection (Fournier's gangrene) have been reported. Pain, redness or swelling in the genital area with fever is checked right away.
Low blood sugar with insulin or a sulfonylurea. Segluromet may raise the risk of low blood sugar with insulin or a medicine that makes the body release insulin, and a lower dose of those may lower the risk.
Vitamin B12 deficiency. Metformin may lower vitamin B12. Blood counts are measured yearly and vitamin B12 every 2 to 3 years.
From the Medication Guide that comes with Segluromet:
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.