Biguanide
Skin side effects of Metformin: rash, dryness, photosensitivity
Skin reactions are among the most visible side effects of medication and range from minor cosmetic concerns to medical emergencies. Metformin (Metformin) at 500mg, 850mg, 1000mg may produce a range of skin effects depending on Metformin; this page covers what is typical, what is rare, and what calls for stopping the medication.
Common skin effects of Metformin
According to the prescribing information for Metformin, common skin reactions include mild rash, dryness, mild itching, transient flushing and (for some agents) photosensitivity that makes the skin more sensitive to UV. Metformin's principal effect is to suppress hepatic glucose production by inhibiting mitochondrial complex I, which raises the cellular AMP/ATP ratio and activates AMP-activated protein kinase. Most are mild, appear in the first weeks and resolve without intervention or with simple measures (moisturiser, sunscreen).
Serious skin reactions
Severe skin reactions — Stevens-Johnson syndrome, toxic epidermal necrolysis, drug-induced hypersensitivity syndrome — are rare but life-threatening. Warning signs are a rash with fever, mucosal involvement (mouth, eyes), skin peeling, or rapidly spreading rash. Any of these on Metformin at 500mg, 850mg, 1000mg is a medical emergency and reason to stop the medication and seek immediate care.
Frequently asked questions
Is a rash on Metformin dangerous? ▾
Most rashes on Metformin at 500mg, 850mg, 1000mg are mild and resolve. A rash with fever, mucosal involvement, blistering or rapid spread is not — it requires emergency evaluation and stopping the medication.
Can Metformin cause sunburn or photosensitivity? ▾
Some medications including a subset of Biguanide agents increase UV sensitivity, making sunburn occur faster. The prescribing information for Metformin lists this when documented. Sunscreen and avoiding peak sun exposure manage the risk.
Products containing Metformin
More on Metformin
- With alcoholMetformin and alcohol — is it safe to drink?
- With foodShould Metformin be taken with food?
- Side effectsMetformin side effects: common, rare and warning signs
- Dosage guideMetformin dosage guide: how much to take and when
- OnsetHow fast does Metformin start working?
- DurationHow long does Metformin last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.