How long do boxed perms last? According to O’Connor, perms can last up to six months; however, unlike hair color, a perm won’t wash out and can’t be chemically reversed. A perm always has to grow out, but thankfully, they typically grow out as natural-looking waves. When it comes to perms, maintenance is key. 2. Short Bob S Curl Perm S컬펌. These perms also look like their namesake with ends that resemble the letter S. 3. Lovely Perm 러블리펌. A Lovely Perm features long, loose, natural looking waves that can start at the top of the head. To try this look at home, a triple barrel hair waver offers dummy proof temporary waves.