Last update: July 11, 2017

Hair straighteners

High Risk for breastfeeding

Poorly safe. Evaluate carefully.
Use safer alternative or interrupt breastfeeding 3 to 7 T ½ (elimination half-lives).
Read the Comment.

Some smoothing products contain formaldehyde or glutaraldehyde (see specific info), especially the keratin smoothing or Brazilian Hair Straightening. Formaldehyde and glutaraldehyde have mutagenic properties and are potentially carcinogenic. Its use has been limited in many countries.

Other straightening products, such as sodium hydroxide, lithium hydroxide, calcium hydroxide or ammonium thioglycolate, used in the so-called Japanese Straightening, are not mutagenic and hence considered safe.

It is recommended to limit its use, avoid products containing formaldehyde, meet the safety standards for use that appear in containers, keep clean the chest area and wear short hair or tied hair to prevent the absorption of potentially toxic compounds by the infant.

Hairdressing's workers are more exposed and must strictly enforce safety rules (gloves wearing and time limitation, etc.) along with the use of legally approved products.

See below the information of these related products:

Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
It is not intended to replace the relationship you have with your doctor but to compound it.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.


Hair straighteners belongs to this group or family:


  1. Peteffi GP, Antunes MV, Carrer C, Valandro ET, Santos S, Glaeser J, Mattos L, da Silva LB, Linden R. Environmental and biological monitoring of occupational formaldehyde exposure resulting from the use of products for hair straightening. Environ Sci Pollut Res Int. 2016 Abstract
  2. Gavazzoni Dias MF. Hair cosmetics: an overview. Int J Trichology. 2015 Abstract Full text (link to original source) Full text (in our servers)
  3. Maneli MH, Smith P, Khumalo NP. Elevated formaldehyde concentration in "Brazilian keratin type" hair-straightening products: a cross-sectional study. J Am Acad Dermatol. 2014 Abstract
  4. Van Lerberghe L, Baeck M. A case of acute contact dermatitis induced by formaldehyde in hair-straightening products. Contact Dermatitis. 2014 Abstract
  5. Couto AC, Ferreira JD, Rosa AC, Pombo-de-Oliveira MS, Koifman S; Brazilian Collaborative Study Group of Infant Acute Leukemia. Pregnancy, maternal exposure to hair dyes and hair straightening cosmetics, and early age leukemia. Chem Biol Interact. 2013 Abstract Full text (link to original source) Full text (in our servers)
  6. Monakhova YB, Kuballa T, Mildau G, Kratz E, Keck-Wilhelm A, Tschiersch C, Lachenmeier DW. Formaldehyde in hair straightening products: rapid ¹H NMR determination and risk assessment. Int J Cosmet Sci. 2013 Abstract
  7. Weathersby C, McMichael A. Brazilian keratin hair treatment: a review. J Cosmet Dermatol. 2013 Abstract
  8. Pierce JS, Abelmann A, Spicer LJ, Adams RE, Glynn ME, Neier K, Finley BL, Gaffney SH. Characterization of formaldehyde exposure resulting from the use of four professional hair straightening products. J Occup Environ Hyg. 2011 Abstract
  9. Mazzei JL, Figueiredo EV, da Veiga LJ, Aiub CA, Guimarães PI, Felzenszwalb I. Mutagenic risks induced by homemade hair straightening creams with high formaldehyde content. J Appl Toxicol. 2010 Abstract
  10. Galiotte MP, Kohler P, Mussi G, Gattás GJ. Assessment of occupational genotoxic risk among Brazilian hairdressers. Ann Occup Hyg. 2008 Abstract

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