If you’re already booked and starting to second-guess, keep reading. We’ll walk you through the science, the safer alternatives, and what we offer at Numi for clients who want smooth hair without the worry.

Why Stylists Hesitate: The Formaldehyde Issue

Traditional keratin treatments — the original Brazilian Blowout formula being the most famous — work by sealing a keratin-rich solution into the hair with a flat iron at high heat. That heat can release formaldehyde gas (or formaldehyde-releasing chemicals like methylene glycol) into the air around you and your stylist.

The FDA has been clear about the risks for years. In their consumer guidance on hair smoothing products, they note that formaldehyde exposure during these services has been linked to eye irritation, headaches, dizziness, respiratory tract problems, nausea, chest pain, and rashes. OSHA has issued hazard alerts about salon air quality, and the FDA has proposed banning formaldehyde and formaldehyde-releasing chemicals in hair straightening products altogether.

Here’s the part that frustrates a lot of clients: some products labeled “formaldehyde-free” actually release formaldehyde when heated, because they contain methylene glycol or other formaldehyde donors that convert into formaldehyde at high temperatures. OSHA found salon owners who had no idea their “safe” products were releasing it because of vague manufacturer labeling.

For a non-pregnant client, the workaround is straightforward: good ventilation, a trained stylist who knows the product chemistry, and an honest conversation about which formulas are truly formaldehyde-free. For a pregnant client, the calculation changes. Even low-level exposure feels harder to justify when there are gentler options available.

What ACOG and Doctors Actually Say

The American College of Obstetricians and Gynecologists (ACOG) hasn’t issued a specific statement on whether you can get a keratin treatment while pregnant, but their broader guidance on chemical exposure during pregnancy is useful context. ACOG recommends that pregnant patients reduce exposure to endocrine-disrupting chemicals where reasonably possible — choosing fragrance-free products, avoiding phthalates and parabens, and being thoughtful about cosmetic chemicals in general.

On hair dye specifically, ACOG’s position is that most hair dye is considered safe during pregnancy because so little is absorbed through the scalp, and animal studies haven’t shown serious birth defects even at high doses. That’s an important data point: not every salon chemical is treated equally. Hair color is one thing. Inhaled formaldehyde for two hours in a salon chair is a different exposure profile.

The cleanest summary we can give you: there is no published study showing that getting a keratin treatment while pregnant directly harms a fetus. There is also no published study confirming it’s safe. Most OB/GYNs we hear back from advise their patients to wait until after delivery (and often after breastfeeding) for any treatment involving formaldehyde or formaldehyde-releasing chemicals. A smaller number give a cautious green light for truly formaldehyde-free smoothing in a well-ventilated salon during the second or third trimester.

Your OB/GYN is the right person to make that call for your specific pregnancy. We say this often, and we mean it — your doctor knows your history, your trimester, any complications, and any sensitivities. We don’t.

Formaldehyde-Free Alternatives Worth Knowing

If you and your doctor decide you’d rather not wait until after delivery, you have real options. Not every smoothing treatment is built on formaldehyde chemistry. A few we offer and trust:

• Keratin Complex — A well-known formaldehyde-free smoothing system. It uses different bonding chemistry to seal keratin into the hair shaft and won’t release formaldehyde gas when heat-styled. Results are softer and shorter-lasting than a traditional keratin, which some clients actually prefer.
• Magic Sleek — A glyoxylic acid-based smoothing treatment, marketed as formaldehyde-free. It’s a popular option for clients who want a more dramatic smoothing effect than a basic conditioning treatment but want to avoid formaldehyde chemistry.
• Lasio Keratin (formaldehyde-free formulas) — Lasio offers both traditional and formaldehyde-free options. The formaldehyde-free formula is gentler and a reasonable choice for clients who want a name-brand keratin without the exposure concerns.
• Deep conditioning and bond-building treatments — Not technically smoothing, but in-salon treatments like Olaplex stand-alone services or rich masks can give you noticeably softer, less frizzy hair for several weeks without any chemical smoothing at all. For a pregnant client who just wants frizz relief, this is often the easiest yes.

If you want a deeper comparison of how smoothing options stack up, our breakdown on the difference between keratin and a Brazilian Blowout walks through the chemistry side by side. We also have a full post on Magic Sleek hair treatment cost if that one’s on your radar. You can also see the full keratin treatment menu at Numi Hair Salon to compare the formaldehyde-free systems we carry.

A Few Honest Things to Consider Before You Book

Even with a formaldehyde-free option and a green light from your doctor, there are a couple of pregnancy-specific factors worth thinking through if you’re asking whether you can get a keratin treatment while pregnant:

• Sitting time. A full smoothing service runs 2–4 hours. If you’re in your third trimester and uncomfortable sitting that long, the experience can be rough. We can build in breaks, but the appointment itself doesn’t get shorter.
• Scent sensitivity. Pregnancy can heighten your sense of smell dramatically. Even gentle smoothing products have a noticeable scent during processing. If you’re someone who’s been nauseated by everyday smells, sitting in a salon for hours surrounded by product smell is a real consideration.
• Hormonal hair changes. Pregnancy hormones can change your hair texture temporarily. Hair that was straight may go wavy; hair that was fine may feel thicker. A smoothing treatment done mid-pregnancy may not give you the same result it would give you six months postpartum, when your texture stabilizes again.
• Timing around breastfeeding. Most stylists who would do a formaldehyde-free smoothing on a pregnant client would also do one on a breastfeeding client. But formaldehyde-based treatments are usually off the table until you’ve finished nursing. If you’re hoping for a traditional Brazilian Blowout, you’re probably looking at a year-plus from now.

If you’d like a refresher on how often you can safely do these treatments long-term, we wrote about that in our post on how often you can get keratin treatments.

What If You Already Got a Keratin Treatment and Just Found Out You’re Pregnant?

Take a breath. There’s no published evidence linking a single past keratin treatment to pregnancy complications, and the exposure window is over. Mention it to your OB/GYN at your next appointment so they have the full picture, but it isn’t a reason to panic. Going forward, you’ll just want to plan around your delivery and breastfeeding timeline.

FAQ

Can you get a keratin treatment while pregnant in the second or third trimester?

Some OB/GYNs give a cautious green light for truly formaldehyde-free smoothing treatments in the second or third trimester, especially in a well-ventilated salon. Most still recommend waiting until after delivery for any treatment involving formaldehyde or formaldehyde-releasing chemicals. The decision really comes down to your specific pregnancy, your doctor’s input, and which keratin system you’re considering. We won’t perform a traditional formaldehyde-based keratin on a pregnant client regardless of trimester.

Is a formaldehyde-free keratin treatment safe during pregnancy?

Safer than a traditional formaldehyde-based treatment — but “safer” isn’t the same as “proven safe.” Formaldehyde-free systems like Keratin Complex, Magic Sleek, and Lasio’s formaldehyde-free line use different bonding chemistry that doesn’t release formaldehyde gas under heat. Many OB/GYNs are comfortable with these in pregnancy, but we still recommend getting your doctor’s approval before booking. Your specific health history matters more than any general guideline.

Can you get a keratin treatment while breastfeeding?

Most stylists treat breastfeeding similarly to pregnancy when it comes to formaldehyde-based keratin treatments — they recommend waiting. Formaldehyde-free smoothing options are usually fine while breastfeeding because the chemistry doesn’t pose the same inhalation risk. As always, run it by your doctor first. If you’re considering a traditional Brazilian Blowout, you’re typically looking at waiting until you’ve finished nursing entirely.

What should I ask my OB/GYN before booking a keratin treatment?

Bring three specific questions: (1) Are you comfortable with me getting a formaldehyde-free smoothing treatment during this trimester? (2) Are there any complications or sensitivities in my pregnancy that change the answer? (3) Would you prefer I wait until after delivery or after breastfeeding? Bringing the exact product name (Keratin Complex, Magic Sleek, etc.) helps your doctor give a more specific answer. A vague “is keratin OK?” question often gets a vague answer.

What are the safest alternatives to keratin treatments during pregnancy?

In-salon deep conditioning treatments and bond-building services like stand-alone Olaplex give you noticeably softer, less frizzy hair for several weeks without any smoothing chemistry. At-home options include weekly hair masks, silk pillowcases, leave-in conditioners, and air-drying instead of heat styling. None of these will straighten textured hair the way a keratin does, but they’ll significantly reduce frizz and improve manageability — which is often what pregnant clients are really after.