Permanent Hair Straightening: Types and Side Effects

Permanent hair straightening treatments are a form of chemical treatment for your hair. Depending on the treatment method you use, naturally curly or textured hair can be modified to lay flat and lose its curl.

These treatments work for several months or longer, and usually last until new hair grows to replace the hair that was treated. For this reason, these processes are called permanent hair straightening.

The label “permanent hair straightening” can be used to refer to keratin treatments, Japanese thermal straightening, and “permanent” straightening processes.

Home treatments and salon treatments are popular options. This article helps you educate yourself on the pros and cons of this type of hair treatment.

There are several types of treatments that claim to make your hair smoother. Each is based on a different chemical formula and processing method.

Some of these treatments are sold in kits that you can do yourself at home, while others require salon-grade equipment to perform effectively.

Professional permanent straightening

A perm refers to a chemical process that permanently alters the hair follicle. Perms are sometimes associated with creating curls in hair that doesn’t naturally have curls, but they can also be used to make hair straight.

Perms are usually done in one salon appointment that takes a few hours. The cost of a perm can vary depending on your salon and the length of your hair. Typically, prices start around $50.

Home permanence

Kits of chemical relaxants can be purchased at pharmacies and beauty supply stores. These treatments claim to offer the same results as a salon perm.

Unless you have formal training in cosmetology, it will be difficult to use these kits effectively. At-home perm options tend to start around $15.

Keratin straightening

Keratin hair treatments and Brazilian blowouts both refer to a method of treating your hair to a smooth texture that lasts 3-5 months.

This method can take several salon appointments to complete the application and usually costs upwards of $150.

Japanese thermal smoothing

Japanese heat straightening, also called acid perm, is more like a traditional “straight” perm than a keratin treatment.

This process may involve the longest time spent in a salon chair (5-6 hours), but it also claims to last up to 6 months. It also costs the most expensive, ranging from $200 to $800.

Hair reattachment

Also called chemical straightening, hair straightening is a process that converts a person’s wavy hair into straight hair. The cost can vary greatly depending on the salon you go to.

Usually it costs $250-$1000 and takes 2-4 hours to complete.

All permanent hair straightening methods use a similar strategy:

  1. A chemical solution is applied to your hair. These chemicals change the way the proteins in your hair are configured.
  2. With perms and Japanese thermal straightening procedures, a neutralizer is then applied to your hair. This neutralizer allows your hair to lock into its new shape, with new bonds forming between the protein molecules in your hair.
  3. You will wait several hours for the chemical solution to infuse into the hair, apply the neutralizer and style your hair.

These chemical solutions often give off strong odors and in many cases you are advised not to get your hair wet or even sweat too much in the days following the treatment.

This means that you walk around inhaling the chemicals used to treat your hair and exposing everyone near you to it.

Hair breakage after a permanent hair straightening treatment is common. The chemical solution basically works by damaging your hair so that it lays flat or releases its natural curl.

A side effect of this damage is that your hair may be harder to comb and take longer to dry until it grows out and new, untreated hair takes its place.

Formaldehyde, a known carcinogen, is also present in most straightening solutions. A study 2021 on hair straightening treatments found levels of formaldehyde deemed high enough to pose a health risk to consumers.

Applying formaldehyde to your hair and inhaling its vapors causes exposure strong enough for side effects, including:

And natural products?

Even “all-natural” or “formaldehyde-free” formulas of hair straighteners are often full of duplicate chemicals that convert to formaldehyde when heated.

Sure, it’s better for your health to look for low-exposure options, but this is one case where reading labels and asking questions won’t necessarily reveal the truth about the product you’re using.

However, there are alternatives. No-lye or alkaline sulfite-based chemical straighteners are safer than other permanent straighteners.

Of course, the safest option is to avoid exposure to harmful chemicals that can be absorbed through your scalp and nasal passages. Straightening your hair without heat is a great alternative when possible.

You should not receive any of these permanent straightening treatments if you are pregnant or trying to become pregnant.

The advantages and disadvantages of each hair straightener depend on the method you are considering.

Permanent hair straightening

Home permanence

Keratin treatments

Japanese thermal straightening

Hair reattachment

The duration may vary depending on the type of treatment you select:

  • Brazilian straightening lasts 3 to 4 months before the natural texture of your hair begins to reappear.
  • Home straightening kits often last no more than 6 weeks.
  • Permanent hair straightening performed in a salon lasts 4 to 6 months.
  • Hair reattachment lasts about 5 to 7 months.
  • Japanese smoothing lasts up to 6 months.

Once your roots start to grow, you’ll usually have to decide whether to repeat the treatment or wait for it to regrow completely.

Permanent hair straightening refers to treatments that make your hair smooth beyond one or two washes. Beyond this vague definition, your results will vary greatly depending on your hair type, how quickly it grows, and the chemical method you use to straighten your hair.

Keep in mind that “permanent” doesn’t mean forever – it just refers to the length of a life cycle of your hair. Talk to your stylist about your options and what they think is best for you.