Love smooth, straight hair? Health risks to know before your next salon visit

There’s something tempting about waking up with smooth, manageable hair, especially in humid weather. But before booking another straightening session, let’s ask what that glossy finish might be hiding.

Think of each strand as a rope with a protective outer covering, the cuticle. Repeated high heat can damage this covering and alter keratin, the protein that gives hair strength. A 2019 laboratory study in the Journal of Cosmetic Dermatology documented heat-related cuticle damage and changes to protein. Over time, hair can become brittle and break. What looks like ‘hair fall’ may actually be strands snapping.

Chemical straightening brings additional concerns. Relaxers change hair’s internal bonds, while some smoothing treatments release formaldehyde when heated. The US FDA warns that this gas can irritate the eyes and lungs, trigger skin reactions and pose cancer risks. Watery eyes, coughing or scalp burning during treatment should never be dismissed as part of the process.

Even ‘formaldehyde-free’ does not automatically mean harmless. In 2024, the New England Journal of Medicine reported a 26-year-old woman who experienced three episodes of acute kidney injury, each following salon straightening. Her product contained glyoxylic acid. This chemical can be converted into oxalate, which can form crystals that damage the kidneys. It’s a serious reminder that something applied to hair can affect organs elsewhere.

Then there is the longer-term question. A 2022 NIH study following more than 33,000 women linked frequent chemical straightener use, over four times in the previous year, with higher uterine cancer risk. Estimated risk by age 70 was 4.05 per cent among frequent users versus 1.64 per cent among never-users. This was an association, not proof of causation, and the findings should not be applied to flat irons alone.

My advice? Make heat styling occasional, use low or medium heat on completely dry hair, and apply a heat protectant. Ask to see salon product ingredients; avoid formaldehyde-releasing and glyoxylic-acid products. ‘Keratin’ and ‘organic’ are not safety guarantees. Stop if treatment causes burning or breathing symptoms. Seek prompt medical care for vomiting, abdominal pain or reduced urination afterwards, and mention the treatment. You can enjoy changing your hairstyle. Just give your hair, scalp and health a say in how often.

(The author is the medical director and business head at Eterne Clinic, Hiranandani Gardens, Powai, Mumbai)

The opinions expressed in this article are those of the author and do not purport to reflect the opinions or views of THE WEEK.