Although the idea of going bald typically conjures images of aging men, hair loss affects people of all genders and ages: Hair can fall out prematurely because of genetic predisposition, drug side effects, or autoimmune disorders. A recent test of two FDA-approved drugs—ruxolitinib and tofacitinib—now suggests that a general treatment for hair loss might be on the way (Sci. Adv. 2015, DOI: 10.1126/sciadv.1500973). A team of researchers at Columbia University had observed that these drugs—approved for the treatment of myelofibrosis and rheumatoid arthritis, respectively—promoted hair growth when fed to mice but also impaired the animals' immune systems. So the scientists thought the compounds might work better when rubbed onto skin. The team shaved mice when their fur was in telogen, the resting stage of a hair follicle's growth cycle. In this stage, hair usually takes more than a month to begin growing back. But treated areas of a mouse's skin fully grew back in