A receding, M-shaped hairline is a sure sign of it. Next, the locks on top of your head start to thin, leaving a bald spot. Eventually, the two meet, and you’re down to a horseshoe pattern of hair around the sides.
It’s easier to hang on to your hair than replace it once it’s gone. But be careful as you explore your options. Most “miracle” products and treatments are shams. When in doubt, your doctor or a dermatologist may be able to help.