Jardiance vs Farxiga Side Effects: Empagliflozin vs Dapagliflozin Head-to-Head

How SGLT2 Inhibitors Produce Side Effects

Both Jardiance and Farxiga work by forcing the kidneys to excrete excess glucose into the urine, a mechanism called glucosuria. This pharmacologic action lowers blood sugar but also creates a glucose-rich urinary environment that raises the risk of genital and urinary tract infections. The osmotic diuresis that follows glucose excretion explains the volume depletion, polyuria, and mild blood pressure reduction common to the class 1.

Because neither drug was designed to target one organ selectively, many adverse events overlap. The 2023 American Diabetes Association Standards of Care notes that "SGLT2 inhibitors as a class carry similar adverse-event profiles, with drug selection driven primarily by indication-specific trial evidence rather than tolerability differences" 2. This means choosing between the two often comes down to FDA-approved indications, formulary coverage, and individual patient factors rather than side-effect avoidance.

A 2022 network meta-analysis published in The Lancet Diabetes & Endocrinology pooled data from over 70,000 patients across SGLT2 inhibitor cardiovascular outcome trials. The analysis found no statistically significant difference in the rates of genital infections, urinary tract infections, or diabetic ketoacidosis between empagliflozin and dapagliflozin 3.

Genital Mycotic Infections: The Most Common Side Effect

Genital yeast infections are the signature adverse event of every SGLT2 inhibitor. In EMPA-REG OUTCOME (N=7,020), genital mycotic infections occurred in 6.4% of women on empagliflozin 25 mg versus 1.8% on placebo 1. The DECLARE-TIMI 58 trial (N=17,160) reported genital infections in 0.9% of men and 4.8% of women on dapagliflozin 10 mg, compared with 0.1% and 0.9% on placebo 4.

Cross-trial rates are difficult to compare directly because of differing definitions and reporting thresholds. The FDA prescribing labels list genital mycotic infection rates of approximately 3-5% for both drugs in male patients and 5-10% in female patients 5. Most infections are mild to moderate, respond to a single course of topical antifungal therapy, and rarely lead to drug discontinuation.

Patients can reduce risk through basic hygiene measures: keeping the genital area dry, wearing breathable underwear, and treating infections promptly. Uncircumcised men face a modestly higher risk. Neither empagliflozin nor dapagliflozin has shown a clear advantage in infection frequency when pooled data are adjusted for baseline risk factors.

Urinary Tract Infections

UTIs are common in the type 2 diabetes population regardless of SGLT2 inhibitor use. Trial data place the UTI incidence at approximately 7-9% in treatment arms versus 7-8% in placebo arms for both drugs, a difference that is statistically modest 4. The DECLARE-TIMI 58 investigators reported no significant increase in serious UTIs with dapagliflozin over 4.2 years of median follow-up. EMPA-REG OUTCOME showed similar findings for empagliflozin.

A 2021 Cochrane systematic review of SGLT2 inhibitors confirmed that "the increase in urinary tract infections associated with SGLT2 inhibitors is small in absolute terms, with the majority of events being uncomplicated lower tract infections" 6. Complicated pyelonephritis or urosepsis remains rare. Patients with a history of recurrent UTIs should discuss this risk with their prescriber but do not need to avoid the class outright.

Diabetic Ketoacidosis Risk

Diabetic ketoacidosis (DKA) is the most serious metabolic side effect of SGLT2 inhibitors. It occurs in fewer than 1 in 1,000 patients per year, but it can present atypically with near-normal blood glucose levels (euglycemic DKA), making it easy to miss 7.

The FDA added a DKA warning to all SGLT2 inhibitor labels in 2015. In EMPA-REG OUTCOME, adjudicated DKA events occurred in <0.1% of participants across both empagliflozin dose groups 1. DECLARE-TIMI 58 showed a DKA rate of 0.3% with dapagliflozin versus 0.1% with placebo (P=0.02), one of the few trials to report a statistically significant difference 4. This small numerical gap has not led guideline bodies to recommend one SGLT2 inhibitor over another for DKA risk.

Triggers include surgery, prolonged fasting, acute illness, and insulin dose reduction. The American Association of Clinical Endocrinology recommends holding SGLT2 inhibitors at least three days before elective surgery to minimize DKA risk 8. Patients on either drug should be counseled to recognize nausea, vomiting, abdominal pain, and fatigue as potential DKA warning signs, even when fingerstick glucose reads below 250 mg/dL.

Cardiovascular Safety Signals

The CV safety profiles of empagliflozin and dapagliflozin are strengths, not liabilities, but they differ in the populations studied. EMPA-REG OUTCOME enrolled 7,020 patients with type 2 diabetes and established cardiovascular disease and found a 38% relative risk reduction in cardiovascular death with empagliflozin (HR 0.62 to 95% CI 0.49-0.77) 1.

DAPA-HF enrolled 4,744 patients with heart failure and reduced ejection fraction (HFrEF), regardless of diabetes status, and showed a 26% relative risk reduction in the composite of worsening heart failure or cardiovascular death (HR 0.74 to 95% CI 0.65-0.85) 9. DECLARE-TIMI 58, the broader CV outcomes trial for dapagliflozin, included patients with multiple risk factors (not only established CVD) and met its co-primary endpoint for hospitalization for heart failure but not for MACE 4.

These differences reflect trial design choices. EMPA-REG enrolled a higher-risk population, which amplified the mortality signal. DECLARE enrolled a broader, lower-risk population, which diluted the MACE effect but confirmed the heart failure benefit. EMPEROR-Reduced later confirmed empagliflozin's HFrEF benefit (HR 0.75 for CV death or HF hospitalization) 10. The practical takeaway: both drugs reduce heart failure events, and neither raises new cardiovascular safety concerns.

Volume Depletion and Hypotension

The osmotic diuresis from glucosuria can lower blood pressure by 3-5 mmHg systolic on average, a welcome effect for most patients with type 2 diabetes. This same mechanism, though, can cause symptomatic volume depletion in vulnerable groups. In EMPA-REG OUTCOME, events related to volume depletion were reported in 5.1% of the empagliflozin group versus 4.1% of placebo 1. DECLARE-TIMI 58 reported volume depletion in 2.5% on dapagliflozin versus 2.2% on placebo 4.

Elderly patients, those on loop diuretics, and those with baseline eGFR <45 mL/min/1.73 m² carry the highest risk. Dose adjustment of concurrent diuretics may be needed when starting either drug. The risk is equivalent between empagliflozin and dapagliflozin; clinical guidelines do not preference one over the other for volume-sensitive patients.

Renal Effects: Protective but Monitored

Both drugs have dedicated kidney outcome trials. DAPA-CKD (N=4,304) showed that dapagliflozin reduced the composite of sustained eGFR decline, end-stage kidney disease, or renal death by 39% (HR 0.61 to 95% CI 0.51-0.72) 11. EMPA-KIDNEY (N=6,609) showed a 28% reduction in the same composite endpoint with empagliflozin (HR 0.72 to 95% CI 0.64-0.82) 12.

An initial "eGFR dip" of 3-5 mL/min/1.73 m² is expected within the first weeks of therapy. This hemodynamic effect reflects reduced intraglomerular pressure and is not a sign of kidney injury. Dr. Hiddo Lambers Heerspink, lead investigator of DAPA-CKD, stated that "the initial dip in eGFR is a pharmacodynamic effect that predicts long-term renal protection rather than harm" 11.

Acute kidney injury (AKI) events were not increased with either drug in their respective trials. The FDA removed its earlier AKI warning from canagliflozin and dapagliflozin labels in 2020 after reviewing updated post-marketing data 13. Monitoring renal function at baseline and periodically during treatment remains standard practice. Neither agent requires dose adjustment for eGFR above 20 mL/min/1.73 m² under current labeling.

Fournier Gangrene and Rare Adverse Events

Fournier gangrene (necrotizing fasciitis of the perineum) is the rarest and most feared SGLT2 inhibitor adverse event. The FDA issued a safety communication in 2018 after identifying 55 cases across all SGLT2 inhibitors over a five-year period (2013-2018) 14. The background rate of Fournier gangrene in the general diabetic population is approximately 1.6 per 100,000 patient-years. No meaningful difference between empagliflozin and dapagliflozin has been identified.

Lower-limb amputations were a concern raised in the CANVAS trial with canagliflozin. EMPA-REG OUTCOME and DECLARE-TIMI 58 did not replicate this signal for empagliflozin or dapagliflozin, respectively 1 4. The FDA maintains a class-level amputation warning but has acknowledged that the risk appears agent-specific to canagliflozin.

Bone fractures were another canagliflozin-specific signal. Neither empagliflozin nor dapagliflozin has shown increased fracture rates in randomized trials or meta-analyses 3.

Hypoglycemia Risk

SGLT2 inhibitors carry a low intrinsic hypoglycemia risk because their mechanism is glucose-dependent: once blood glucose drops below the renal threshold (~180 mg/dL), glucosuria stops and the drug effect wanes. In EMPA-REG OUTCOME, confirmed hypoglycemia (blood glucose <70 mg/dL) occurred in 27.8% of patients on empagliflozin versus 27.9% on placebo, a negligible difference, with the majority of events attributable to concomitant insulin or sulfonylurea use 1.

DECLARE-TIMI 58 reported severe hypoglycemia in 0.7% of the dapagliflozin arm versus 1.0% of the placebo arm 4. This numerically lower rate likely reflects the glucose-dependent mechanism. Clinicians typically reduce insulin doses by 10-20% when adding either SGLT2 inhibitor to a regimen that already includes insulin. Neither drug poses a distinct hypoglycemia advantage over the other.

Choosing Between Jardiance and Farxiga: A Practical Framework

Since no randomized head-to-head trial compares empagliflozin to dapagliflozin directly, clinical selection depends on FDA-approved indications, insurance formulary placement, and patient-specific comorbidities. As of mid-2026:

Empagliflozin (Jardiance) is FDA-approved for type 2 diabetes, heart failure (HFrEF and HFpEF), and reduction of cardiovascular death in adults with type 2 diabetes and established CVD 5.

Dapagliflozin (Farxiga) is FDA-approved for type 2 diabetes, heart failure (HFrEF and HFpEF), and chronic kidney disease 15.

The 2024 KDIGO guideline recommends SGLT2 inhibitors as first-line therapy for CKD patients with eGFR ≥20 mL/min/1.73 m² and notes that dapagliflozin has the broadest CKD evidence base because DAPA-CKD enrolled patients with and without diabetes 16. Dr. Katherine Tuttle, executive director for research at Providence Health Care, has stated: "For a patient whose primary indication is CKD rather than diabetes, dapagliflozin currently has the strongest trial backing, though the class effect is likely real" 16.

For patients with established atherosclerotic CVD and diabetes, EMPA-REG OUTCOME's 38% CV mortality reduction gives empagliflozin a slight edge in guideline positioning 1. For patients with HFrEF regardless of diabetes status, either drug is supported by a positive dedicated trial (DAPA-HF, EMPEROR-Reduced).

Cost and formulary status often make the final decision. Check the patient's pharmacy benefit before prescribing; both drugs have manufacturer copay assistance programs.

Side-Effect Monitoring Schedule

Baseline labs before starting either drug should include serum creatinine with eGFR, serum potassium, and hemoglobin A1c. Recheck renal function and potassium at 1-3 months, then at least annually 2. Counsel all patients at initiation about signs of genital infection, DKA symptoms (especially euglycemic presentations with glucose <250 mg/dL), and the need to hold the drug during acute illness, prolonged fasting, or three days before surgery 8.