Safety guide
Is keratin treatment safe?
The honest answer: it depends on the product. Some keratin treatments contain formaldehyde — a known carcinogen. Others are completely formaldehyde-free and safe for home use. Here is how to tell the difference.
The real risk
Formaldehyde is the problem. Not keratin.
Keratin is a natural protein already in your hair. It is not harmful. The issue is how some treatments deliver it. Traditional Brazilian blowouts and older keratin treatments use formaldehyde or methylene glycol as a bonding agent. When heated with a flat iron at 230°C, these chemicals release formaldehyde gas.
Formaldehyde is classified as a Group 1 carcinogen by the International Agency for Research on Cancer. Short-term exposure causes eye and throat irritation, headaches, and breathing difficulty. Long-term repeated exposure is linked to nasopharyngeal cancer.
In March 2026, the UK Office for Product Safety and Standards recalled a keratin treatment for containing prohibited levels of formaldehyde. This is not rare — many products labelled “formaldehyde-free” contain methylene glycol, which converts to formaldehyde when heated.
Formaldehyde treatments
Avoid
Toxic fumes when heated
QIQI Hair Controller
Safe
Formaldehyde-free
UK product recalls (2025–26)
3+
Formaldehyde violations
QIQI formaldehyde level
0%
Independently verified
Check your labels
Ingredients to avoid.
If you see any of these on a keratin treatment label, do not use the product — especially not at home without professional ventilation. These are all forms of formaldehyde or chemicals that release formaldehyde when heated.
Formaldehyde
Listed directly — banned above 0.2% in EU/UK cosmetics
Methylene glycol
Converts to formaldehyde when heated. The most common loophole.
Formalin
A solution of formaldehyde in water. Same chemical, different name.
Methanal
The IUPAC chemical name for formaldehyde.
Methanediol
Another name for methylene glycol. Same conversion to formaldehyde.
Timonacic acid
Used in some treatments — may release formaldehyde under heat.
What is safe
Formaldehyde-free keratin treatments.
Modern keratin treatments use glyoxylic acid or cysteine-based formulas instead of formaldehyde. They achieve the same smoothing and frizz-control results without toxic fumes. QIQI Hair Controller uses a cysteine-based formula. Nanokeratin System uses a nano-particle keratin technology. Both are independently verified as formaldehyde-free.
These treatments are safe to apply at home in a normal bathroom. No special ventilation needed. No fume exposure risk. The same products are used daily in UK salons. Read more in our formaldehyde-free keratin treatment guide.
£119 · 150g
Hair Controller — Thick & Coarse
Formaldehyde-free permanent smoothing treatment for thick, coarse, and afro-textured hair. Softens disulfide bonds under heat for lasting frizz control — from defined curls to fully straight. QIQI Hair Controller results last up to 5 months.
Shop now →
£119 · 150g
Hair Controller — Wavy & Curly
Permanently reduces frizz and enhances natural pattern definition — or delivers a smooth, controlled finish. Designed specifically for wavy and curly hair. Formaldehyde-free. Lasts up to 5 months.
Shop now →
£119 · 150g
Hair Controller — Thin & Delicate
Formaldehyde-free permanent smoothing for fine, colour-treated, or delicate hair. Eliminates frizz and reduces volume without over-processing. QIQI Hair Controller safe for bleached and highlighted hair. Results last up to 5 months.
Shop now →Preventing damage
How to avoid hair damage from keratin treatment.
Do a strand test first
Apply the treatment to a small section of hair 48 hours before full application. Check for any adverse reaction, breakage, or excessive straightening.
Use the right formula for your hair type
Thick & Coarse for afro and resistant hair. Wavy & Curly for naturally curly hair. Thin & Delicate for fine, bleached, or colour-treated hair. Using too strong a formula on fine hair can over-process it.
Do not apply within 4 weeks of bleaching
Bleached hair has a compromised cuticle. Keratin treatment on recently bleached hair can cause breakage. Wait at least 4 weeks — ideally 6.
Control your flat iron temperature
230°C is the standard processing temperature. Higher temperatures do not improve results — they risk heat damage. Use a quality flat iron with accurate temperature control.
Do not overlap treatments
Wait until the previous treatment has grown out before reapplying. Applying keratin on top of existing keratin treatment can over-process the mid-lengths.
Follow the aftercare
Use sulfate-free shampoo from the first wash. Sulfates strip the treatment and can leave hair dry. Read our guide on the best shampoo after keratin treatment.
Common questions
Keratin treatment safety — FAQ
Is keratin treatment safe for your hair?
Formaldehyde-free keratin treatments like QIQI Hair Controller are safe when used correctly. They do not break disulfide bonds permanently — they soften and restructure them under heat. The risk comes from treatments containing formaldehyde or methylene glycol, which release toxic fumes when heated. Always check the ingredients list and choose formaldehyde-free products.
Can keratin treatment damage your hair?
Incorrect application can cause damage — specifically using too high a temperature, processing too long, or applying to recently bleached hair. When applied correctly with the right formula for your hair type, keratin treatments improve hair condition by reducing porosity and sealing the cuticle. Always do a strand test first.
Is keratin treatment safe during pregnancy?
Formaldehyde-based treatments are not recommended during pregnancy due to fume exposure. Formaldehyde-free treatments like QIQI Hair Controller do not release toxic fumes, but we recommend consulting your doctor before any chemical hair treatment during pregnancy or breastfeeding.
How do I know if a keratin treatment contains formaldehyde?
Check the ingredients for: formaldehyde, methylene glycol, formalin, methanal, or methanediol. These are all forms of formaldehyde or formaldehyde-releasing chemicals. If a product says "formaldehyde-free" but contains methylene glycol, it is not truly formaldehyde-free — methylene glycol converts to formaldehyde when heated.
Is keratin treatment safe for coloured hair?
Yes, but use the right formula. QIQI Hair Controller Thin & Delicate is designed for colour-treated hair. Apply keratin treatment at least 2 weeks after colouring. The treatment can actually help seal colour in, making it last longer. Do not apply within 4 weeks of bleaching.
What are the side effects of keratin treatment?
With formaldehyde-free treatments: temporary hair stiffness in the first 72 hours (before the first wash), possible slight volume reduction on very fine hair. With formaldehyde-containing treatments: eye and throat irritation, headaches, respiratory issues, and long-term cancer risk from repeated exposure. This is why we only stock formaldehyde-free products.
Is it safe to do keratin treatment at home?
Yes, with a formaldehyde-free product and proper preparation. Read the full application guide before starting, do a strand test, ensure good ventilation, and use the correct formula for your hair type. QIQI Hair Controller is used in professional salons and designed to be safe for home application with the same instructions.
How often can you safely do keratin treatment?
Every 3–5 months, or when the previous treatment has grown out. There is no benefit to overlapping treatments. Wait until you notice your hair returning to its natural texture before reapplying. Applying too frequently can over-process the hair.
Related guides
Formaldehyde-Free Keratin Treatment
Deep dive into safe keratin formulas and what makes them different.
Keratin Treatment at Home
Step-by-step guide to applying keratin treatment yourself.
How Long Does It Last?
What affects results and how to get the full 5 months.
Best Shampoo After Keratin
Why sulfate-free matters and which shampoos to use.
Formaldehyde-free · Salon-grade · Safe at home
Safe treatments. Real results.
Every treatment we stock is formaldehyde-free. The same products UK hairdressers use — available for you to apply at home.