Can metformin cause pruritus?

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Last updated: April 30, 2026 • View editorial policy

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Can Metformin Cause Skin Itching?

Yes, metformin can cause skin itching (pruritus), though this is not listed among the most common side effects in the FDA labeling.

Evidence from FDA Drug Labeling

The FDA label for metformin 1 lists the most common adverse reactions (occurring in >5% of patients) as:

  • Diarrhea (53%)
  • Nausea/Vomiting (26%)
  • Flatulence (12%)
  • Asthenia (9%)
  • Indigestion (7%)
  • Abdominal Discomfort (6%)
  • Headache (6%)

Pruritus is not explicitly mentioned in the common side effects section of the FDA labeling 1. However, the label does note that rash and sweating were reported in 1-5% of patients 1.

Documented Cases of Metformin-Induced Pruritus

Despite the absence of pruritus in the common side effects list, multiple case reports document serious dermatological reactions to metformin that include pruritus as a prominent symptom:

Severe Dermatological Reactions

  • DRESS Syndrome: A 40-year-old man developed rash, generalized pruritus, lymphadenopathy, and eosinophilia after metformin treatment, representing the first reported case of Drug Rash with Eosinophilia and Systemic Symptoms (DRESS) syndrome linked to metformin 2. The patient improved with drug withdrawal.

  • Erythroderma: A 62-year-old man experienced a 4-year history of pruritus and erythroderma while taking metformin for 5 years, with skin biopsy confirming metformin-induced erythroderma and lichenification 3.

  • Cholestatic Hepatitis: A 68-year-old man developed jaundice and pruritus 4 weeks after starting metformin, with liver biopsy revealing severe cholestasis 4. The pruritus in this case was likely related to cholestatic liver injury rather than direct skin effects.

Clinical Implications

If a patient on metformin develops pruritus, consider the following approach:

  1. Assess severity and associated symptoms: Look for accompanying rash, fever, lymphadenopathy, jaundice, or systemic symptoms that might indicate serious reactions like DRESS syndrome or hepatotoxicity.

  2. Rule out other causes: Evaluate for unrelated dermatological conditions, contact allergies, or other medications.

  3. Monitor for progression: Isolated mild pruritus may be tolerable, but worsening symptoms or development of rash warrants immediate evaluation.

  4. Consider discontinuation: For significant pruritus, especially with systemic symptoms or rash, discontinue metformin and observe for improvement 3, 2.

  5. Obtain appropriate testing: If hepatic symptoms are present (jaundice, right upper quadrant pain), check liver enzymes and consider hepatobiliary imaging 4.

Important Caveats

  • Pruritus is rare but documented: While not among the common side effects, case reports establish metformin as a potential cause of pruritus, particularly in the context of serious hypersensitivity reactions.

  • Time course varies: Onset can range from weeks to years after initiation 3, 4.

  • High index of suspicion needed: Because pruritus is not widely recognized as a metformin side effect, clinicians must maintain awareness of this possibility to avoid delayed diagnosis 2.

The absence of pruritus from the common side effects list does not exclude metformin as a cause when a patient presents with itching, particularly if accompanied by other dermatological or systemic manifestations.

References

3
Research

Erythroderma and Chronic Lichenification Due to Metformin.

European journal of case reports in internal medicine, 2019

4
Research

Metformin-induced cholestatic hepatitis.

Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 2003

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This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.