The surprising benefits of red light

Photograph: Getty Images

Jul 20th 2026|5 min read

Oozing mouth ulcers are one of the many possible side-effects of radiation and chemotherapy treatments for cancer. The ulcers make it hard for patients to eat, worsening their suffering. Some must be fed by tube. A new way of treating these ulcers could brighten the future, however: light-emitting diodes (LEDs) tuned to the red end of the spectrum and placed into a patient’s mouth improve symptoms in more than 40% of cases.

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