Keratin treatment side effects

For most people, a well-done keratin smoothing treatment causes no lasting problems. But it is still a chemical service sealed with high heat, and side effects do happen. Most are linked to three things: the ingredients in the formula, the heat used to seal it, and the condition of the hair before treatment. Knowing these lets you ask the right questions before you sit in the chair.

This page explains common side effects in general terms. It is not medical advice. If you have a skin condition, asthma or any reaction after a treatment, speak to a doctor or dermatologist.

Some traditional keratin smoothing formulas contain formaldehyde, or ingredients that release formaldehyde when heated, such as methylene glycol. Formaldehyde is a known irritant, and health agencies in several countries have issued warnings about salon exposure to it. When these formulas are flat-ironed, fumes can irritate the eyes, nose and throat of both the client and the stylist.

Formulas labelled formaldehyde-free use other smoothing agents and are generally less irritating, though they may give a slightly softer result or need more frequent repeats. Be aware that a 'formaldehyde-free' label is not always reliable: check the ingredient list for formaldehyde, formalin, methylene glycol and methanediol, and ask your salon to show you the product before they start.

Watering eyes, a stinging nose, coughing or a scratchy throat during the flat-iron stage are the most commonly reported short-term effects. They are a sign of fumes from the formula. Choose a salon with good ventilation and, if possible, extraction near the chair. If irritation is strong, ask the stylist to stop. People with asthma or breathing problems should talk to a doctor before having any keratin service.

Redness, itching or a burning feeling on the scalp can happen if the product is applied too close to the roots or if you are sensitive to an ingredient. A good stylist keeps the formula a small distance from the scalp.

Always ask for a skin patch test at least 48 hours before treatment. Do not proceed if you react, and seek medical advice for swelling, blistering or a rash that does not settle.

Some people notice more hair coming out in the weeks after a treatment. Often this is breakage rather than hair falling from the root: high flat-iron heat applied to weak, bleached or over-processed lengths can make strands snap. Tight ponytails and clips in the days after treatment can also leave dents and stress the hair.

If shedding continues, or you notice thinning patches, see a dermatologist. Hair fall has many causes, including diet, stress and hormones, and a treatment is not always the reason.

Over-processed hair can feel dry or straw-like after keratin, especially if a sulfate shampoo is used afterwards. Keratin can also make hair colour look slightly lighter or fade faster, so many stylists recommend colouring a week or two before, not straight after. Very fine hair can feel limp, so ask for a lighter application if your hair is thin.

Choose a trained professional and an experienced salon. Ask what formula is being used and read the ingredients. Do a skin patch test and a strand test. Tell your stylist about colour, henna, bleach or previous rebonding. Avoid treatments if your hair is already breaking — repair it first. Make sure the room is well ventilated. Follow the aftercare exactly.

Wait at least 72 hours before washing, unless your stylist says otherwise. Then use a sulfate-free shampoo, a conditioning mask once a week and a light serum on the ends. Use heat protection before blow-drying or straightening.

If you are pregnant or breastfeeding, have asthma or another breathing condition, or have an active scalp problem such as broken skin, eczema or a severe dandruff flare-up, speak to your doctor before having any keratin service. Many salons will ask you to wait.

Hair that is already breaking, very porous after bleaching, or has been chemically treated in the last few weeks is also at higher risk. In those cases a strengthening routine for six to eight weeks is a better first step than another chemical treatment.

Keratin smoothing involves applying a formula evenly section by section and sealing it with a flat iron at high temperature. Getting the amount, the drying and the iron passes right takes practice, and mistakes are what lead to breakage and fumes. For a first treatment, use a trained professional in a well-ventilated salon. If you choose an at-home kit, read and follow every instruction, work in an open, ventilated space, and do the patch and strand tests first.

Contact your stylist, and a doctor if needed, if you notice any of these: a scalp that stays red, sore or itchy beyond a day or two; blisters or weeping skin; hair that snaps when you comb it; patches of shedding; or breathing problems after the service. Do not cover up a reaction with more products. Gently rinse with cool water and get advice.

Mild dryness or a slightly flat feel in the first week is common and usually improves with conditioning care.

Keep a note of the product name and batch used at the salon, and photograph the pack if you can. If you do react, this information helps a doctor or dermatologist understand what you were exposed to, and helps you avoid the same formula next time. A responsible salon will share it without any fuss.