What can I realistically expect from a keratin treatment?

My starting point would be the result you want to live with at home. Less frizz is not the same as straight hair, and easier styling is not the same as no styling. A treatment can change how hair feels and behaves without delivering a wash and go version of the polished salon finish. Before deciding, I would want a clear explanation of what the proposed product can reasonably achieve for your hair and what it cannot promise.

Keratin is not one treatment formula

Keratin is a broad label used for different smoothing services and formulations. It does not tell you which ingredients are in the bottle, how the service works or whether two products have the same risks. I would ask for the exact product name rather than judge a service by its category or a familiar brand name alone.

Ask about the hair after the salon finish

The smooth finish you see at the end of a service includes the effect of blowdrying and ironing. A photograph taken then cannot tell you exactly what your hair will look like after a home wash or when left to air dry. I would ask those questions explicitly, especially if your main aim is to avoid using heat or spending time styling.

Depending on the formulation and your hair, curls may loosen or change and volume may reduce. That may suit someone seeking less fullness, but disappoint someone who wants the same curls with less frizz. I would not promise that your curl pattern will remain identical, or that an unwanted change can be instantly reversed. Describe what you want to keep as clearly as what you want to change.

A softer feel does not answer the suitability question

Cosmetic smoothing does not regrow hair, cure hair loss or permanently repair split ends. Hair feeling softer afterwards is not proof that damaged hair can tolerate more chemical processing. I would keep the desired appearance separate from the condition of the hair being treated.

Bleaching, colour history, porosity, previous chemical services and the current condition of the hair all matter, alongside the curl and volume you hope to retain. Fine hair and heavily processed hair raise different questions. A useful assessment explains why this particular product may or may not suit your hair, rather than assuring you that every hair type is suitable.

A strand assessment may help a practitioner assess the hair's response. It cannot rule out systemic health risks or all allergic reactions. A patch test, keeping a product away from the scalp or following marketing instructions is not proof that the whole service is safe.

The ingredient and safety questions deserve a direct answer

Formaldehyde free or no added formaldehyde describes a particular claim about a product. By itself it does not establish that nothing is released during use, or that the other active ingredients and the rest of the formulation are safe. The US Food and Drug Administration explains that some hair smoothing products contain or release formaldehyde gas when heated. That does not mean every keratin product does. It means the exact ingredients, safety data sheet, practitioner training and ventilation are meaningful questions, and the FDA information describes a hazard rather than stating UK legal requirements.

Glyoxylic acid is a separate ingredient concern. In its January 2025 review, the French health agency ANSES concluded that a link between glyoxylic acid based hair straightening treatments and acute kidney injury was highly likely, and advised avoiding products containing it pending further assessment. This is not a diagnosis of everyone who has had smoothing, a blanket ban on all keratin services or a statement that a UK legal ban applies. Not all keratin formulas are the same, and one ingredient being absent does not settle the safety of another.

The evidence is still developing. The European Commission's call for safety data on glyoxylic acid closed on 8 April 2026, and on 4 May 2026 its Scientific Committee on Consumer Safety was formally asked to give a scientific opinion on the safety of glyoxylic acid in cosmetic products. That is a requested assessment, not a final clearance or a ban. A 2026 exposure study of two marketed formulations reported low exposures and no health concerns under the conditions it tested, though several authors were affiliated with product manufacturers. That finding does not establish that every formulation or application is safe.

I would pause rather than recommend proceeding with a glyoxylic acid formulation while the exact product and its safety evidence are being reviewed. A product specific decision needs the actual product name, ingredient list and safety data sheet, considered alongside the current independent evidence.

What should practitioners ask their suppliers?

• What is the exact current formulation and full ingredient list, and does it match the stock actually being supplied?
• Can you provide the current safety data sheet and the written directions for professional use?
• What exactly does a formaldehyde free or no added formaldehyde claim mean, what evidence supports it, and what is released under actual heating and rinsing conditions?
• Which smoothing actives are used instead, and what is the current evidence for systemic as well as local risks?
• How have you responded to the ANSES findings on glyoxylic acid?
• What is the basis of the safety assessment for the intended professional use, what limitations and contraindications apply, and how are formulation changes and incidents reported?

A safety data sheet is hazard communication, not independent clearance. Marketing claims, patch or strand tests and simply following instructions do not eliminate every risk. Practitioners cannot certify the toxicological safety of a formulation themselves. Where a supplier's evidence is unclear, the right step is to seek competent safety advice rather than repeat a reassuring claim.

There is no universal first wash or colour timetable

Colour timing, when to wash, home care and reapplication instructions depend on the product. I would not apply a universal 72 hour rule or assume that instructions remembered from a previous treatment still apply. Ask for the directions for the exact formulation in writing, including how they fit with your colour plans.

Nor would I promise a fixed lifespan. Your hair, the formulation and care routine affect the experience, and a manufacturer's estimate is not a guarantee for you. Reapplication should involve reassessing the hair and the product, not automatically repeating a service because a set period has passed.

Questions I would take to the appointment

• What is the exact product, and what result is realistic after my first home wash and when my hair air dries?
• How might it change my curls and volume, and what styling could still be needed?
• What about my condition and chemical history could make it unsuitable?
• Can you explain the ingredients, safety data sheet and current safety evidence, including any glyoxylic acid or formaldehyde concerns?
• What are this product's colour timing and home care instructions, and what limits apply to longevity claims?
• When should my hair and the product choice be reassessed, rather than simply repeating the treatment?

My practical takeaway is to ask for the exact product, a realistic home result and a product specific explanation of the ingredients and evidence before deciding. If either answer is missing, pause. For practitioners, the matching discipline is not to repeat broad reassuring claims without product specific justification. A beautiful finish is not a substitute for knowing what is being applied, what changes you may have to live with and whether the available evidence supports proceeding.