Could Topical Minoxidil Cause Non-Arteritic Anterior Ischemic Optic Neuropathy?

In 2016, a case report was presented involving a 42-year-old male who developed non-arteritic anterior ischemic optic neuropathy (NAION) after using a high amount of topical 5% minoxidil solution for androgenetic alopecia. The patient experienced sudden blurring of vision in his left eye after using double the normal dose of minoxidil for a year. His vision improved after discontinuing minoxidil, but blurred vision recurred in the other eye 11 months later. Upon stopping minoxidil again, his vision improved. The Naranjo probability algorithm score indicated a possible drug-induced reaction with a score of 4. The report suggested that while there is no definitive cause-and-effect relationship established between topical minoxidil use and NAION, the potential for such a side effect should be considered, especially in cases without other predisposing factors. The authors called for further long-term studies with larger patient groups to investigate this rare adverse effect.