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Despite the name, perms don't leave you with permanent ringlets. Curls generally last two to four months. You'll shorten the lifespan of your perm by shampooing with the wrong product. The best shampoos for perms protect the curl and nourish the hair, which is pretty stressed after the perm process. After the initial setting period, wash the permed hair as often as you like.
Right after a perm, your hair needs time to rest. Professionals call the first 24 hours after a perm the "settling in" period. Do not wash your perm at all during this time, or you'll wash those curls right out.
The perm process exposes your hair to lots of drying chemicals. While modern perms are gentler than your mother's perms, they still leave hair vulnerable. Moisturizing shampoo that's specially formulated for permed hair gently cleans the hair. It deposits much-needed moisture. Find one at your local beauty supply store, then use whenever you wash your permed hair. Since the hair shafts and ends are more vulnerable than the roots, lather those areas more than the roots.
What to Avoid
An alkaline shampoo is too harsh for new perms. It can loosen your curl or remove the curl altogether. Clarifying shampoos and other alkaline products swell the hair shaft so cleaning agents can penetrate. The chemicals that set your perm can wash out when the hair shaft swells. Your shampoo bottle won't have a pH written on it. Moisturizing shampoos are generally acidic, while clarifying shampoos are generally alkaline. A shampoo that's marked as pH-neutral is okay to use, but a moisturizing shampoo is your best bet.
Be gentle when you perm, comb and style your hair. Scrubbing the hair too hard while you shampoo can cause the curls to relax, as can the wrong shampoo. Treat your hair with a conditioner for permed hair, since your regular product may condition too much or not enough.