Permanent Hair Straightening: Types And Side Effects - Healthline

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HealthlineSubscribeEverything You Want to Know About Permanent Hair Straightening

Medically reviewed by Cynthia Cobb, DNP, APRN, WHNP-BC, FAANP — Written by Kathryn Watson — Updated on May 23, 2023

Types of treatments
How it works
Side effects
Pros and cons
How long does it last?
Takeaway

There are many types of permanent hair straightening options However, all use chemicals that cause damage to the hair.

Permanent hair straightening treatments are a form of chemical processing for your hair. Depending on which method of processing you use, hair that’s naturally curly or textured can be altered to lay flat and lose its curl.

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

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

Self at-home treatments and salon treatments are both popular options. This article helps you be informed about the pros and cons of this kind of hair treatment.

Types of treatments

There are several types of treatments that claim to make your hair straighter. Each relies 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 be done 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 it, but they can be used to make hair straight, too.

Perms are usually done in one salon appointment that takes a few hours. The cost of a perm can vary according to your salon and how long your hair is. Typically, prices start around $50.

At-home perms

Chemical relaxant kits can be purchased at pharmacies and beauty supply stores. These treatments claim to offer the same results as a perm from a salon.

Unless you have formal cosmetology training, it will be tricky 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 for a straight texture that lasts 3 to 5 months.

This method can take multiple salon appointments to finish the application, and it typically costs over $150.

Japanese thermal straightening

Japanese thermal hair straightening, also called an acid perm, is more similar to a traditional “straight” perm than it is to a keratin treatment.

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

Hair rebonding

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

Usually, it costs between $250 and $1,000 and it takes 2 to 4 hours to complete.

How it works

All permanent hair straightening methods use a similar strategy:

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

These chemical solutions often carry strong scents, and in many cases, you’re cautioned against getting your hair wet or even sweating too much in the days following the treatment.

This means you’re walking around inhaling the chemicals used to treat your hair, and you’re exposing everyone near you to them.

Side effects

Hair breakage after a permanent hair straightening treatment is common. The chemical solution works by, in essence, damaging your hair so it lies flat or releases its natural curl.

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

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

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

respiratory difficulties
irritation to your nose and eyes
skin redness and irritation
increased risk of breast cancer

What about natural products?

Even “all-natural” or “formaldehyde-free” formulas of hair straighteners are often full of duplicate chemicals that become formaldehyde when they’re heated.

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

However, there are some alternatives. Chemical straighteners that are lye-free or alkaline sulfite-based are safer than other permanent hair straighteners.

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

You shouldn’t get any of these permanent straightening treatments if you’re pregnant or trying to become pregnant.

Pros and cons

The pros and cons of each hair straightening depend on what method you’re considering.

Permanent hair straightening

Pros of permanent hair straightening

Permanent straightening at the salon is the cheapest of the salon options for getting results, and it’s the least time-consuming.
It lasts for up to 6 months.

Cons of permanent hair straightening

Perms work by damaging your hair follicles, so they can’t hold their natural shape.
Split ends, breakage, and hair loss can occur. You’re also exposing your body to harmful chemicals during the perm process.
After getting a perm, you can’t color-treat or otherwise modify your hair, and you won’t be able to wear it curly, even if you want to.

At-home perms

Pros of at-home perms

DIY hair-straightening kits you can get at the pharmacy are affordable.
They claim to be simple to use.
They don’t require hours spent in a salon chair, and the chemicals are approved for home use, which means they may be less concentrated.

Cons of at-home perms

For the most part, you’re not going to get salon results with a home straightening solution.
You could damage your hair to the same extent, or a greater extent, that you would if you went to a stylist.
Some consumers have reported that home hair straightening kits don’t last longer than a single wash.

Keratin treatments

Pros of keratin treatments

Keratin treatments claim to condition your hair.
These treatments last 4 to 6 months, which is a significant amount of time in comparison with other hair straightening treatments.

Cons of keratin treatments

Keratin treatments are semi-permanent, meaning that after a few months, the results start to wash out.
Your hair won’t return to its natural state, and you might not like the look of how new hair growth looks at the crown of your head.
Most of these treatments also contain harmful chemicals, even if they claim to be free of them.

Japanese thermal straightening

Pros of Japanese thermal straightening

Japanese hair straightening makes hair easy to maintain.
Results are long lasting, with hair typically staying straight until new hair growth appears.

Cons of Japanese thermal straightening

This method of hair straightening damages your hair just like other options. It also contains dangerous chemicals that you breathe in and absorb through your skin.
Japanese thermal straightening is quite expensive and takes hours to complete the process.
Once your hair starts to grow back, there’s often a stark contrast between the hair that’s been treated and your natural hair at the root.
People who get this kind of hair straightening sometimes need touch-ups several times a year.

Hair rebonding

Pros of hair rebonding

This process eliminates frizz and straightens hair.
You can expect long-term results that last until new hair grows in.

Cons of hair rebonding

Most hair rebonding formulas contain formaldehyde, which can result in increased risk of health effects, such as breast cancer and respiratory issues.
Hair rebonding makes it difficult to style until new hair grows in.
Because this process gets your hair straighter than any other process listed, it causes even more damage to your hair than other methods.

How long does it last

The length can vary based on the type of treatment you select:

Brazilian hair straightening lasts 3 to 4 months before your natural hair texture starts to reappear.
Home hair straightening kits don’t often last longer than 6 weeks.
Permanent hair straightening done in a salon lasts anywhere from 4 to 6 months.
Hair rebonding lasts about 5 to 7 months.
Japanese hair straightening lasts up to 6 months.

Once your roots start to grow in, you’ll usually need to decide if you’re going to repeat the treatment or wait for it to grow out completely.

The bottom line

Permanent hair straightening refers to treatments that make your hair straight beyond a wash or two. Beyond that vague definition, your results will vary widely according to 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 duration of one life cycle of your hair. Speak to your hairstylist about your options, and what they think might be the best one for you.

How we reviewed this article:

SourcesHistoryHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

De Paula JNH, et. al. (2022) Effects of chemical straighteners on the hair shaft and scalp.https://www.sciencedirect.com/science/article/pii/S0365059621003147
Eberle CE, et. al. (2019) Hair dye and chemical straightener use and breast cancer risk in a large US population of black and white women.https://onlinelibrary.wiley.com/doi/full/10.1002/ijc.32738
Goossens A, et al. (2022). Contact allergy to and allergic contact dermatitis from formaldehyde and formaldehyde releasers: a clinical review update.https://onlinelibrary.wiley.com/doi/full/10.1111/cod.14089
Zhang Y, et al. (2015). Effect of shampoo, conditioner and permanent waving on the molecular structure of human hair.https://peerj.com/articles/1296/

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Medically reviewed by Cynthia Cobb, DNP, APRN, WHNP-BC, FAANP — Written by Kathryn Watson — Updated on May 23, 2023

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Types of treatments

Professional permanent straightening

At-home perms

Keratin straightening

Japanese thermal straightening

Hair rebonding

How it works

Side effects

What about natural products?

Pros and cons

Permanent hair straightening

Pros of permanent hair straightening

Cons of permanent hair straightening

At-home perms

Pros of at-home perms

Cons of at-home perms

Keratin treatments

Pros of keratin treatments

Cons of keratin treatments

Japanese thermal straightening

Pros of Japanese thermal straightening

Cons of Japanese thermal straightening

Hair rebonding

Pros of hair rebonding

Cons of hair rebonding

How long does it last

The bottom line

How we reviewed this article:

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