Tell it to Me Straight! Japanese Hair Straightening 101

Curated by Claudia Shannon / Research Scientist / ishonest

No need to jet set, though. You could visit your local salon or get a Japanese hair straightening kit. (But bear in mind that Japanese hair straightening is permanent until it’s grown out — so only go down the DIY route if know what you’re doing. Get it wrong, and it stays wrong.)

Here are the whats, whys, benefits, and risks of Japanese hair straightening.

What is Japanese hair straightening?

ishonest No.501 - Frizzy Hair

No.501 - Frizzy Hair

In the U.S., Japanese hair straightening is gaining popularity. It had a brief period of popularity in the early ’00s, but it became less commonplace as keratin treatments began to take off.

Fast-forward to 2021 and, after years of growing dissatisfaction at the high risk and low reward of keratin alternatives, hair straightening Japan-style is regaining the top spot again — one formaldehyde-free treatment at a time.

Japanese hair straightening was, somewhat unsurprisingly, invented in Japan. Japanese folks had been rocking the chemically straight look for a whole 10 years prior to its emergence in the New York fashion scene.

Risks and rewards of Japanese hair straightening

As with all things, there are pros and cons to Japanese hair straightening. They might also risk hair damage. If you’re unsure about the possible side effects of any hair treatment that uses chemicals, it’s a great idea to AMA your stylist.

How is Japanese hair straightening different than other treatments?

For strong and hydrated hair

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Japan doesn’t have a monopoly on the hair straightening market. There are plenty of other options available if this method doesn’t feel like the right fit for you.

Here’s a brief rundown of how Japanese hair straightening compares to other common salon straightening treatments.

Japanese hair straightening vs. keratin straightening

Keratin hair straightening is a popular choice for people who want their waves gone. Keratin naturally occurs in nails and (importantly) hair. It’s a protein, and hair products from shampoos to pills use it for its healthy hair benefits.

A fair amount of debate circulates around keratin. There’s a lot of comparison between Japanese hair straightening and a keratin treatment called a “Brazilian blowout” or “Brazilian keratin treatment.”

ishonest No.231 - Pigmentation & Blemishes

No.231 - Pigmentation & Blemishes

There isn’t much cost difference between the two. Keratin straightening treatment takes much longer though. We’re talking about a 2-day treatment that takes 2 to 4 hours each day. That’s a real commitment. And for all that time, your hair will only remain straight for 3 weeks.

Another big difference is the use of formaldehyde-based cream in keratin straightening. This is a huge draw of Japanese hair straightening — there’s none of that here.

You may have heard of formaldehyde. It’s up there with uranium, asbestos, and lead paint on the list of stuff our Grandparents used to put in everything before they figured it can have pretty serious health consequences.

So while they have similar costs, thermal reconditioning is faster, lasts longer, and doesn’t require formaldehyde. Your move.

Japanese straightening vs. relaxer
Volume and structure for your hair

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There are many different varieties of hair relaxers. It’s a blanket term for lotions and creams that make curly hair easier to straighten.

Retailers sell a bunch of different chemical mixtures as relaxers. But most are alkali-based, with sodium or calcium hydroxide among the most common base ingredients. These are harsher on your hair than the cystine and ammonium thioglycolate solutions that play a role in Japanese straightening.

Relaxed hair may not be as healthy as hair that’s had the Japanese treatment. Relaxers strip an entire layer from the structure of your hair, where thermal reconditioning only breaks the bonds between layers. This is a pretty huge difference.

Relaxers are cheaper, certainly. However, their effects also only last for about 6–8 weeks. If you only want a short-term commitment to straight hair (like if you have a wedding or prom coming up), then having your curls relaxed may be your preferred choice.

ishonest No.401 - Dark Circles

No.401 - Dark Circles

For longer-term defrizzing though, Japanese straightening is the safer (albeit pricier) choice for you.

Straight to the point

Japanese hair straightening is also known as thermal reconditioning. It’s gaining popularity in salons across the U.S. There are a few scare stories that suggest that it can be dangerous for hair. But, in truth, it’s no more dangerous than most other salon treatments.

The key ingredient is a straightening solution which contains a chemical formula whose active components are cystine and ammonium thioglycolate. Japanese straightening follows a similar process to other chemical treatments (rinsing, conditioner, neutralizer, etc.), but the stylist straightens your hair in small sections.

As far as costs go, it can set you back $400+, and that’s at the cheap end. The treatment takes 2 to 3 hours at least), but you won’t need to repeat it for around 6 months.

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