Metformin vs. Farxiga

See how Metformin and Farxiga compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Metformin is a first-line oral biguanide that lowers blood sugar and has decades of safety data, while Farxiga is an SGLT2 inhibitor also approved for heart failure and chronic kidney disease.

  • Metformin mainly causes GI side effects like diarrhea and nausea, while Farxiga's main risks are genital yeast infections and urinary tract infections.

  • Doctors often prescribe them together, since metformin and Farxiga work through different mechanisms and can be combined for added blood sugar control.

Metformin vs. Farxiga Drug Summary

Metformin

Metformin is a biguanide that lowers blood sugar mainly by reducing glucose production in the liver and improving insulin sensitivity. It's approved for type 2 diabetes in adults and children 10 and older, and comes as an immediate-release tablet, extended-release tablet, or oral solution taken with meals.

Farxiga

Farxiga is an SGLT2 inhibitor that lowers blood sugar by causing the kidneys to remove excess glucose through urine. Beyond type 2 diabetes, it's approved to reduce heart failure hospitalizations and slow chronic kidney disease progression, and it's taken as a single tablet once a day.

Metformin vs. Farxiga Side Effects

Metformin

Most common
diarrhea (>5%)
nausea/vomiting (>5%)
flatulence (>5%)
asthenia (>5%)

Farxiga

Most common
female genital mycotic infections (up to 6.9%)
nasopharyngitis (up to 6.3%)
urinary tract infections (up to 4.3%)
back pain (up to 4.2%)

Metformin vs. Farxiga Dosage

Metformin

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 500 mg twice daily Week 1
Maximum dose 500 mg once daily Week 1
Dose changes 2 increases As tolerated

Farxiga

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 5 mg once daily At the start
Maximum dose 10 mg once daily If needed
Dose changes 1 increase As tolerated

Metformin vs. Farxiga Indications

Metformin

Metformin is FDA-approved to control blood sugar in adults and children 10 and older with type 2 diabetes. It's also used off-label for polycystic ovary syndrome and for prediabetes or weight management, though it's not approved for type 1 diabetes or diabetes prevention.

  • Type 2 diabetes in adults and children 10+

  • Off-label: polycystic ovary syndrome (PCOS)

  • Off-label: prediabetes and weight management

  • Not approved for type 1 diabetes

Farxiga

Farxiga is FDA-approved to control blood sugar in people with type 2 diabetes and to reduce heart failure hospitalizations in adults with or without diabetes. It's also approved to slow kidney function decline in chronic kidney disease, but it isn't approved for type 1 diabetes or diabetic ketoacidosis.

  • Type 2 diabetes in adults and children 10+

  • Heart failure, reduced or preserved ejection fraction

  • Chronic kidney disease to slow decline

  • Not approved for type 1 diabetes

Metformin vs. Farxiga Pros and Cons

Metformin

Metformin remains the standard starting medication for type 2 diabetes because of its long safety record and low cost. Its main downsides are gastrointestinal side effects and a boxed warning for lactic acidosis in people with kidney problems.

Pros

  • Roughly $4 to $30 per month, far cheaper than Farxiga

  • Decades of real-world safety data

  • Low risk of hypoglycemia on its own

  • Available as tablets or oral solution for flexible dosing

Cons

  • Common GI side effects like diarrhea and nausea

  • Boxed warning for lactic acidosis

  • Contraindicated in severe kidney impairment

  • No proven heart failure or kidney disease benefit

Farxiga

Farxiga offers benefits beyond blood sugar control, with approvals for heart failure and chronic kidney disease. It costs substantially more than metformin and carries a distinct set of genitourinary and metabolic risks.

Pros

  • Approved for heart failure and chronic kidney disease

  • Once-daily dosing with no titration needed

  • Avoids the GI side effects common with metformin

  • May reduce cardiovascular death risk in heart failure

Cons

  • Roughly $400 to $785 per month, much pricier than metformin

  • Risk of genital yeast infections and UTIs

  • Can cause ketoacidosis even with near-normal glucose

  • Not recommended for glucose control at low kidney function

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