Ruxolitinib found to cause eyelash growth: a case report

BACKGROUND Hypereosinophilic syndrome is a hematologic disorder in which the eosinophils proliferate. Oral Janus kinase inhibitors are known to be effective treating hypereosinophilic syndrome. Janus kinase inhibitors have also demonstrated efficacy in alopecia. Madarosis is a condition in which the eyelashes are missing or absent and can been seen in alopecia patients. CASE PRESENTATION We present the case of a 77-year-old Asian man who was diagnosed with hypereosinophilic syndrome, refractive to all medications except ruxolitinib. He responded well. It was noted unexpectedly that his eyelashes grew much longer than they were normally. CONCLUSIONS Previous studies have demonstrated an improvement in alopecia areata, with increased hair growth on the head and eyebrows. This study demonstrates that longer eyelashes may be another effect of oral Janus kinase inhibitors. We report the first case of eyelash elongation and thickening in a patient taking ruxolitinib. Physicians and patients should be aware of the side effect of these Janus kinase inhibitors. Further investigation is needed to ascertain whether ruxolitinib or other interleukin inhibitors can aid in the treatment of madarosis.