Transient vision loss and achromatopsia associated with use of minoxidil

A man in his early 20s presented with complaints of a throbbing headache for 1 week and blurred vision for 2 weeks. He had been using oral minoxidil tablets (2.5 mg of minoxidil and 10 000 mcg of biotin) two times per day and topical 5% minoxidil for alopecia (hair and beard) during the same period. On examination, both anterior and posterior segment evaluations were within normal limits, except for hyperaemic optic discs in both eyes. He could only read the demo plates on the Ishihara colour vision chart. Given the absence of genetic factors, an adverse drug reaction to minoxidil was suspected. Consequently, both oral and topical minoxidil were discontinued during the initial visit. The vision improved and the achromatopsia resolved after the cessation of minoxidil, without further intervention.