On one wrist, I have a birthmark; on the other is a scab. It started as a mosquito bite, I think. I'd picked it until it bled, until it turned my brown flesh pink. Then, one day, I left my scab alone. And again the day after that. I left it until new skin grew over it. But this new skin is leathery and rugged; it has ridges and contours. My index finger pokes and prods. I realise what's about to happen but can't stop. “Please, don't,” I tell my nails as they angle themselves against my scar. “Not again,” I whisper, as they pierce flesh. I close my eyes and work my nails under and around, pulling and twisting until the darkened leather comes loose and blood breaks free.
It wasn't until my early twenties that I learned my compulsion to pick at my skin had a name. Skin picking disorder (also known as dermatillomania or excoriation disorder) is part of the family of body-focused repetitive behaviours (BFRBs), which includes hair pulling (trichotillomania) and biting your nails, lips or cheeks. There are few reliable statistics for their prevalence, but it's thought that as many as one in 20 suffer
