Glyoxylic Acid and Hair Smoothing: What You Need to Know After the ANSES Alert

By Paris Liss — Experts in professional hair smoothing for over 25 years

(Updated 02/07/2026)

Since late 2024, glyoxylic acid has received particular attention following an alert issued by ANSES (the French Agency for Food, Environmental and Occupational Health & Safety) concerning several cases of acute kidney failure that occurred after the use of certain hair smoothing products.

At Paris Liss, our priority is to provide transparent information so that you can choose the hair smoothing technology best suited to your needs.

What is glyoxylic acid?

Glyoxylic acid (Glyoxylic Acid) is an ingredient used in certain hair smoothing treatments to temporarily modify the hair structure under the heat of a straightening iron.

It has gradually replaced formaldehyde in many formulations because of its effectiveness on difficult, very curly or voluminous hair.

Today, several hair smoothing technologies coexist on the market:

• glyoxylic acid-based smoothing treatments;
• tannin-based smoothing treatments;
• technologies combining different organic acids and amino acids;
• manufacturer-specific formulations.

Each technology has its advantages, limitations and application protocol.

The ANSES alert: key points

In October 2024, ANSES, the French Directorate General for Health and the DGCCRF issued a statement concerning several cases of acute kidney failure reported after the use of certain hair smoothing products containing glyoxylic acid.

The published data reported:

• 26 cases recorded in France in 2023;
• several new cases reported in 2024.

ANSES is continuing its work to better understand the mechanisms involved and assess which regulatory measures may be necessary.

As a precaution, it recommends that professionals and consumers remain vigilant when using these products.

Symptoms that should prompt rapid medical advice

If, in the hours following a smoothing treatment, you experience:

• abdominal pain;
• lower back pain;
• nausea;
• vomiting;

it is recommended to seek medical advice promptly or contact a poison control centre, stating that a hair smoothing product was used.

Poison control centres

• Paris : 01 40 05 48 48
• Lyon : 04 72 11 69 11
• Marseille : 04 91 75 25 25
• Bordeaux : 05 56 96 40 80
• Lille : 08 00 59 59 59
• Nancy : 03 83 22 50 50
• Angers : 02 41 48 21 21
• Toulouse : 05 61 77 74 47

How can you tell whether a smoothing treatment contains glyoxylic acid?

The most reliable method is to check the product's INCI ingredient list.

The ingredient generally appears under the name:

• Glyoxylic Acid

It should not be confused with other ingredients with similar names.

Some commonly encountered ingredients

Our commitment at Paris Liss

For over 25 years, we have selected professional products that meet demanding quality and compliance criteria.

All products sold in our shop are:

✅ formaldehyde-free;

✅ free from formaldehyde-releasing agents;

✅ selected from recognised manufacturers;

✅ compliant with the regulatory requirements applicable to the European market.

Our catalogue now includes several hair smoothing technologies to meet the different needs of professionals.

Some products use glyoxylic acid, while others rely on different technologies, such as tannin or other smoothing systems.

Each product page specifies the product's characteristics, and its composition is available through the INCI ingredient list.

Which technology should you choose?

There is no single smoothing treatment suitable for every type of hair.

The choice depends in particular on:

• the nature of the hair;
• previous chemical treatments;
• the desired level of straightening;
• any scalp sensitivity;
• the professional's experience.

For example, our Salvatore Blue Gold uses a different technology and does not contain glyoxylic acid.

Conversely, other professional smoothing treatments use this technology to achieve performance suited to certain hair types.

It is essential to always follow the manufacturer's protocol carefully.

How to choose the right smoothing treatment

Before purchasing, we recommend:

• checking the INCI ingredient list;
• checking the manufacturer's recommendations;
• carrying out a hair diagnosis;
• following the processing times;
• using an appropriate straightener temperature.

A well-chosen professional smoothing treatment is above all one suited to the client's hair type.

FAQ

Do all Brazilian smoothing treatments contain glyoxylic acid?

No.

Several smoothing technologies exist today. Some products use glyoxylic acid, while others use tannin or other smoothing systems.

Is glyoxylic acid banned in France?

As of the date this article was written, no.

However, ANSES is continuing its expert assessment and recommends caution when using the products concerned.

How can you tell whether a product contains glyoxylic acid?

By checking its INCI ingredient list.

The ingredient generally appears under the name Glyoxylic Acid.

Are all Paris Liss products formaldehyde-free?

Yes.

No product sold in our shop contains formaldehyde or formaldehyde-releasing agents.

Are there smoothing treatments without glyoxylic acid?

Yes.

Some technologies, such as our Salvatore Blue Gold, use a different process.

Do Paris Liss products comply with European standards?

Yes.

We exclusively select products that meet the regulatory requirements applicable to the European market.

In summary

Our advice

Every head of hair is unique. There is no universal “best” smoothing treatment, but rather one suited to your hair type and expectations.

If you are unsure between several technologies, our team is available to help you choose and guide you towards the product best suited to your situation.

Paris Liss — Experts in professional hair smoothing and care for over 25 years. We select professional products recognised for their quality, effectiveness and compliance, to offer both professionals and consumers high-quality solutions for caring for their hair.