Metformin Side Effects

Medically reviewed byEditorial Medical Review, MD, NAMS-CMP

Last reviewed: 5/27/2026 · Verify credentials →

Metformin side-effect incidence rates below are drawn from FDA prescribing information and clinical trials. Most common effects are gastrointestinal and peak during dose changes.

Common side effects(5)

Incidence rates from clinical trials. Individual experience varies.

Metformin common side effects with incidence rates
Effect	Incidence	Note
Diarrhea	~25%	Most common; reduced with extended-release form
Nausea / upset stomach	7-25%	Take with food; titrate slowly
Metallic taste	~3%
Abdominal discomfort	6-12%
Decreased appetite	5-10%

Serious side effects(2)

Less common but require medical attention.

Lactic acidosis (rare). Very rare; risk rises with kidney impairment, dehydration, contrast dye
Vitamin B12 deficiency. With long-term use — periodic B12 monitoring advised

Managing side effects(4)

Take with meals to reduce GI upset
Extended-release (XR) form causes far less diarrhea — ask about switching
Titrate slowly (start 500 mg, increase weekly) to build GI tolerance
Get periodic B12 levels checked on long-term therapy

Telehealth providers that prescribe Metformin(5)

Independently reviewed providers offering Metformin for PCOS. Editorial ranking — affiliate links don't affect order.

Allara
90/100
Comprehensive PCOS and hormonal health telehealth. Multidisciplinary care team including endocrinologists, dietitians, and mental health professionals.
Pollie (PCOS Specialist)
85/100
PCOS-focused platform with phenotype-driven treatment matching. Specialist providers only.
Curio Wellness PCOS
80/100
Integrative PCOS platform combining endocrinology, dietitian visits, and mental health support.
Pollie
77/100
PCOS-focused care platform combining clinician access with personalized supplement protocols. Subscription model with medication and supplement bundling.
Felix Health PCOS
77/100
Async PCOS prescribing for acne, hirsutism, and irregular cycles. Affordable monthly plans.

We don't sell Metformin or any medication. These are editorial reviews of telehealth providers — clicking through may earn us a commission, which does not affect our scoring.

Sources(3)

Was this Metformin side-effects guide helpful?

Metformin Side Effects

Medically reviewed byEditorial Medical Review, MD, NAMS-CMP

Last reviewed: 5/27/2026 · Verify credentials →

Metformin side-effect incidence rates below are drawn from FDA prescribing information and clinical trials. Most common effects are gastrointestinal and peak during dose changes.

Common side effects(5)

Incidence rates from clinical trials. Individual experience varies.

Metformin common side effects with incidence rates
Effect	Incidence	Note
Diarrhea	~25%	Most common; reduced with extended-release form
Nausea / upset stomach	7-25%	Take with food; titrate slowly
Metallic taste	~3%
Abdominal discomfort	6-12%
Decreased appetite	5-10%

Serious side effects(2)

Less common but require medical attention.

Lactic acidosis (rare). Very rare; risk rises with kidney impairment, dehydration, contrast dye
Vitamin B12 deficiency. With long-term use — periodic B12 monitoring advised

Managing side effects(4)

Take with meals to reduce GI upset
Extended-release (XR) form causes far less diarrhea — ask about switching
Titrate slowly (start 500 mg, increase weekly) to build GI tolerance
Get periodic B12 levels checked on long-term therapy

Telehealth providers that prescribe Metformin(5)

Independently reviewed providers offering Metformin for PCOS. Editorial ranking — affiliate links don't affect order.

Allara
90/100
Comprehensive PCOS and hormonal health telehealth. Multidisciplinary care team including endocrinologists, dietitians, and mental health professionals.
Pollie (PCOS Specialist)
85/100
PCOS-focused platform with phenotype-driven treatment matching. Specialist providers only.
Curio Wellness PCOS
80/100
Integrative PCOS platform combining endocrinology, dietitian visits, and mental health support.
Pollie
77/100
PCOS-focused care platform combining clinician access with personalized supplement protocols. Subscription model with medication and supplement bundling.
Felix Health PCOS
77/100
Async PCOS prescribing for acne, hirsutism, and irregular cycles. Affordable monthly plans.

We don't sell Metformin or any medication. These are editorial reviews of telehealth providers — clicking through may earn us a commission, which does not affect our scoring.

Was this Metformin side-effects guide helpful?