Solutions for a bad perm include conditioning the hair back to health, trimming any "fishtail" ends, and cutting the hair frequently while it grows out. While hydrating and conditioning the hair can be done at home, professional help is often needed for more drastic responses to a bad perm.
Applying a hot oil treatment to the hair helps to recondition it and restore some of the moisture lost through perming. Wrap plastic wrap over hair treated with hot oil and leave it on for at least an hour for best results. Deep-conditioning products are also sometimes helpful to repair damage caused by a perm. Look for products that include plant proteins, such as quinoa or barley extracts, as well as sandalwood.
Sometimes perm damage is localized at the end of the hair strands; this often occurs if the perm rods weren't wound properly when the perm was done. These "fishtail" ends can often be trimmed individually without requiring a full haircut. Don't cut until at least three days after the perm to prevent any further damage to the hair. Minor trimming can be done at home, or a professional hairstylist can tackle the problem conclusively.
When hair is badly damaged by a perm, trimming and moisturizing will not solve the problem because the hair's molecular structure has been damaged. In this case, the hair must be cut as short as possible and allowed to grow back out. Ask for a layered cut that removes damaged ends while still allowing some length.