“Keratin is a naturally occurring protein in the hair, and keratin treatments, in general, are designed to semi-permanently make the hair straighter, softer, and shinier” explains Vernon François, celebrity hairdresser, educator, and founder of Vernon François Haircare; global inclusivity and education advisor for Kérastase; and global consultant, educator, and celebrity hairdresser for Redken. “There are different types that vary in intensity, ingredients, required time, application process, and cost.”
According to Los Angeles–based hairstylist Sophie Rose Gutterman, a regular keratin treatment will typically last anywhere between three and six months (depending on at-home upkeep, lifestyle, hair texture, etc.) while an express treatment can last anywhere between six weeks and three months, depending on the same types of factors. Another cardinal rule of keratin treatments? Steer clear of water and ponytails for three days, minimum, as they can bend and add texture to freshly relaxed strands.
Additionally, it’s important to make the differentiation between smoothing treatments (like Goldwell Kerasilk), which also contain keratin but are less potent, formaldehyde-free, and more geared toward frizz, and straightening treatments (like Brazilian Blowout) which are stronger, harsher on the hair, and really iron out the texture. In other words, make sure you talk to a stylist you trust and ensure you know what you’re actually getting before diving headfirst at the salon.