Keratin hair treatments that smoothen and straighten the hair have been a growing trend, popularly known as Brazilian keratin treatment or a Brazilian blowout. It involves the application of products to the hair, blow-drying it, and then using a flat hair iron to seal it.
Usually, keratin from chicken feathers or other animal sources is extracted and applied naturally or as a hydrolyzed product to the hair.
Keratin is the natural protein of your skin, hair, and nails. It comprises the main structure of the hair and is made up of cysteine, which is around 20% of the total amino acid residues.
Keratin forms the intramolecular and intermolecular disulfide bonds (1) that are responsible for the elasticity and strength of the hair. (2)
However, a keratin treatment is bad for your hair in many ways.
Why Keratin Treatment Is Bad for Hair
Chemical hair treatments, such as keratin treatments, bleaching, and coloring, cause hair damage by breaching the hair fiber and cleaving keratin K31, which leads to decreased tensile strength. The intact protein is required to restore or improve the mechanical strength of the damaged hair fibers. (3)
Note: Formaldehyde and other aldehydes used in the keratin treatment process are not straightening products but crosslinking agents. (4) The World Health Organization, International Agency for Research on Cancer, United States Environmental Protection Agency, and Oregon Occupational Safety and Health Division classify formaldehyde as a carcinogen. (5)
Why Is Keratin Treatment Done?
Keratin treatments are prevalent worldwide because of marketing gimmicks claiming that it is a natural way to make hair more manageable and shinier. (4)
Many keratin hair treatment products are currently available. Still, the mechanism is the same – the hair is blow-dried to break the hydrogen bonds of the natural keratin to allow the hydrolyzed keratin to penetrate the hair and crosslink with natural hair keratin.
The process is made possible with the crosslinking agent formaldehyde (a derivative of formalin or methylene glycol) and a flat hair iron. (5)
Consequences of Keratin Hair Treatments
Here are some of the drawbacks of keratin hair treatments:
- Experts found that within 5 days of keratin treatment, people started losing vast chunks of hair, ending up with a loss of around 40% hair volume. (6)
- Keratin treatment involves dissolving the hair bonds to help smoothen the hair, but it weakens your hair, causing breakage in the mid shaft, especially after repeated treatments.
- The high heat temperature of the flat hair iron used to smoothen the hair can damage the hair follicles, leading to hair breakage and fall. Without the flat hair iron, it is impossible to get the desired effects of keratin treatment as the hair straightener ensures the protein treatment binds to each strand.
- Chemically treated hairs get worn off in the cuticle, leading to hair fiber fractures that make the hair hydrophilic. Moreover, when the hair is exposed to high concentrations of straightening chemicals for a long duration, the hair becomes more porous.
- The pH of the chemical formulations of the hair treatments can also affect hair strength – a low pH results in better straightening of the hair but lesser hair strength, and vice versa. The high heat of the hot tools can also lead to the denaturation of hair proteins and cause hair damage. (7)
Side Effects of Keratin Hair Treatments on Health
Here are some side effects of keratin treatment on health:
- Keratin treatments affect the nasal cavity and cause coughing, wheezing, eye irritation, contact dermatitis, and other allergic reactions.
- The strong chemicals used during the keratin treatment cause scalp irritation, which can be avoided by applying scalp barriers before applying the product.
- Some people who had keratin treatments reported experiencing eye irritation, which can be mitigated by using eye shields.
- More than half of the people who undergo keratin treatment choose not to do it again due to the harm that it causes. But it is still necessary to educate the public because people are interested in doing these treatments despite these harmful side effects. (8)(5)
General Queries Related to Keratin Hair Treatments
Can formaldehyde cause cancer?
Exposure to high amounts of formaldehyde has been linked to some forms of cancer in humans, but the effects of exposure to small amounts are yet unclear. (9)
How long does the effect of keratin hair treatments last?
A keratin treatment takes a few hours to be done in the hair, depending on its length and thickness. Its effects can last up to 6 months or longer depending on the product used and the post-treatment hair care.
Keratin treatments help to soften, smoothen, and enrich the hair, but in the long run, it can be harmful to your strands as formaldehyde, a carcinogen, is used in the process. (9)
Note: Before trying a keratin treatment, check with your dermatologist first to ensure your scalp is healthy and free from psoriasis.
- Keratin. Keratin – an overview | ScienceDirect Topics. https://www.sciencedirect.com/topics/materials-science/keratin.
- Feroz S, Muhammad N, Ranayake J, Dias G. Keratin – based materials for biomedical applications. Bioactive materials. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7171262/. Published April 16, 2020.
- Basit A, Asghar F, Sadaf S, Akhtar MW. Health Improvement of human hair and their reshaping using recombinant keratin K31. Biotechnology reports (Amsterdam, Netherlands). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6218806/. Published October 24, 2018.
- A; WCMM. Brazilian keratin hair treatment: A Review. Journal of cosmetic dermatology. https://pubmed.ncbi.nlm.nih.gov/23725308/.
- Hair smoothing treatments: Perceptions and wrong practices among … https://www.jddsjournal.org/article.asp?issn=2352-2410;year=2019;volume=23;issue=1;spage=20;epage=23;aulast=Algarni.
- Showing the destructive impact keratin hair straignteners and Brazilian blowout. Environmental Working Group – Know your choices. https://www.ewg.org/hair-straighteners/our-report/adverse-reactions-and-injuries-hair-straighteners/.
- What do we need to know about hair straightening? – researchgate. https://www.researchgate.net/publication/354152688/.
- Department of Labor Logo United Statesdepartment of Labor. 1910.1048 App C – Medical surveillance – Formaldehyde | Occupational Safety and Health Administration. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1048AppC.
- Formaldehyde. American Cancer Society. https://www.cancer.org/healthy/cancer-causes/chemicals/formaldehyde.html.