Metformin and photosensitivity
Pro Research Analysisby 
Searched over 200M research papers
Metformin and Photosensitivity: Clinical Case Insights
Photosensitivity as a side effect of metformin is rare but has been documented. In a report of three cases, patients developed photosensitive skin reactions after starting metformin, with symptoms appearing between 22 days and 4 years after initiation. The skin lesions appeared on sun-exposed areas and were either eczematous or erythematous. Importantly, these lesions resolved after discontinuing metformin, and a positive rechallenge confirmed the drug’s role in at least one case. This evidence suggests that, although uncommon, metformin can cause photosensitivity in some individuals .
Metformin and Light-Based Cancer Therapies
Metformin as a Potential Photosensitizer in Photodynamic Therapy
Recent research has explored whether metformin could act as a functional photosensitizer in cancer treatment. In vitro studies combining metformin with laser irradiation (without traditional photosensitizers) showed increased cytotoxicity against head and neck cancer cells. The combination was more effective than either treatment alone, suggesting that metformin may enhance the effects of light-based therapies, though further research is needed to confirm if metformin itself acts as a photosensitizer .
Metformin and Radiosensitivity in Cancer Cells
Enhanced Radiosensitivity in Lung and Colorectal Cancer
Multiple studies have shown that metformin increases the radiosensitivity of various cancer cells, including non-small cell lung cancer (NSCLC) and colorectal cancer. In NSCLC, metformin enhances the effect of radiation and chemotherapeutic agents like cisplatin, making cancer cells more susceptible to treatment. This effect is linked to molecular changes such as increased DNA damage, reduced DNA repair, and destabilization of protective proteins like NRF2 25. In colorectal cancer, metformin’s radiosensitizing effect is associated with modulation of the p53/miR-34a/SIRT1 feedback loop, leading to increased apoptosis and reduced cell viability in resistant cancer cells .
Conclusion
Metformin is rarely associated with photosensitivity, but documented cases confirm it can occur. In cancer therapy, metformin may enhance the effects of light-based and radiation treatments, possibly acting as a photosensitizer or radiosensitizer. These findings highlight the need for awareness of potential skin reactions in patients on metformin and suggest new avenues for its use in combination cancer therapies 12345.
Sources and full results
Most relevant research papers on this topic