How to Read an INCI List and Check Your Products for Banned Ingredients
If you’ve ever flipped over a bottle of gel polish and found yourself squinting at a list of long, complicated ingredient names, you’re definitely not the only one wondering what you should be looking for.
With the 2026 cosmetics regulation changes in Great Britain, it’s more important than ever for salon owners and nail techs to know how to check ingredient lists.
You might have heard that TPO is affected, but that doesn’t always mean you’ll spot the letters “TPO” on your bottle.
The good news is that you don’t need to be a cosmetic chemist to make some basic checks of your professional stock.
This guide breaks down what an INCI list is, where to find it, and which ingredient names are most helpful to spot when you’re checking your salon products.
The quickest way to start?
Look at the ingredient list and look for the full INCI name, not just the abbreviation or the name you’ve seen floating around on social media or in industry updates.
What Is an INCI List?
INCI stands for International Nomenclature of Cosmetic Ingredients. Put simply, it’s the standardised system of names used to identify cosmetic ingredients.
This is why the back of a beauty product can sometimes look considerably more complicated than the front.
The ingredient you know by a short or familiar name may appear under a much longer INCI name.
TPO is a perfect example.
If you’re checking a nail product for TPO, don't simply search the ingredient list for the letters “TPO”. The name you need to recognise is:
Trimethylbenzoyl Diphenylphosphine Oxide
TPO is one of the substances affected by the 2026 changes to cosmetics regulations in Great Britain.
CTPA confirms that TPO is the cosmetically relevant ingredient among the group of 16 CMR substances added to the prohibited substances list, with the placing-on-market deadline having taken effect on 15 August 2026.
For more information about the regulation itself and the relevant deadlines we have a handy guide coming up!
Where to Find the INCI List on Salon Product Packaging
Before you can check a product, you need to find its ingredient list – and this isn't always as obvious as it sounds.
Depending on the product and its packaging, you may find the ingredients:
- printed directly on the bottle, jar or tube;
- on the base or back of the container;
- on the product's outer box or packaging;
- on an attached label, leaflet or tag where applicable.
Tiny bottles like gel polish can be especially tricky to read. Good lighting and your phone’s zoom are your best friends here - snap a pic and zoom in to make things easier.
Already binned the outer packaging? Don’t guess -check the info from the manufacturer or reach out to your supplier for the exact ingredient details on that product.
Remember that formulations can change, too.
An ingredient list found online may not necessarily relate to the exact bottle or batch sitting on your shelf.
Step-by-Step: Checking Your Product for Banned Ingredients
If you’re sorting through a cupboard full of salon stock, don’t make it harder than it needs to be. Go through your products one by one and jot down anything you need to double-check.
Step 1: Find the INCI List on the Product or Outer Packaging
Start with the physical product.
Look over the bottle, jar or tube and any outer packaging you still have. You're looking for the ingredients section rather than the product's marketing claims.
If the print is tiny, snap a clear photo and zoom in on your phone.
Can’t find an ingredient list anywhere? Set that product aside and check with the manufacturer or supplier—don’t try to guess the ingredients just from the product name.
Step 2: Search for TPO by Its Full INCI Name
If you use professional gel nail products, this is one of the most important things to check during your stock audit.
Look for:
Trimethylbenzoyl Diphenylphosphine Oxide
That’s TPO.
Under the 2026 Great Britain cosmetics changes, TPO was added to Annex II and is therefore prohibited for use in cosmetic products.
The deadline for placing affected products on the market was 15 August 2026, with a making-available/off-shelf deadline of 14 February 2027 under the published CTPA guidance.
If you spot TPO in a product, don’t panic or assume you’ve done something wrong just because you found an older bottle. What you do next depends on the regulatory dates and how “making available” is interpreted in Great Britain.
Step 3: Check for Formaldehyde-Releasing Preservatives
This is where it's important not to muddle two different regulatory changes.
Some ingredient names you may come across when checking salon products include:
- DMDM Hydantoin
Imidazolidinyl Urea
Diazolidinyl Urea
Quaternium-15
These are examples of formaldehyde-releasing preservatives.
However, finding one of these names does not automatically mean you've found a newly banned ingredient.
The 2026 change concerns the threshold at which relevant finished cosmetic products must carry the warning “releases formaldehyde”.
From 15 July 2026, that threshold changed from 0.05% to 0.001% formaldehyde in the finished product.
You also cannot work out from an INCI list alone how much formaldehyde a finished product releases. That information needs to come from the manufacturer or Responsible Person.
Step 4: Check for 4-MBC if You Stock Relevant Sun Protection Products
Another ingredient affected by the 2026 changes is the UV filter 4-Methylbenzylidene Camphor (4-MBC).
Under the updated GB rules, 4-MBC was added to the prohibited substances list. The deadline for placing affected products on the market was 15 July 2026, with the making-available/off-shelf deadline on 14 January 2027.
It’s worth checking this if your salon stocks any cosmetic products with UV filters.
Again, note that this has different deadlines from TPO.
Don't assume that every ingredient affected by the 2026 regulatory changes follows the 15 August 2026 and 14 February 2027 dates.
Quick Reference: Ingredient Names for Salon Professionals
When you’re in the stockroom with a bottle in one hand and your phone in the other, you definitely don’t want to scroll through pages of regulations.
Here are some of the main names covered in this guide:
|
Ingredient Name
|
Short Name | What it means |
|
Trimethylbenzoyl Diphenylphosphine Oxide
|
TPO | Prohibited in GB cosmetics under the 2026 changes |
|
4-Methylbenzylidene Camphor
|
4-MBC | UV filter prohibited in GB cosmetics under the 2026 changes |
|
DMDM Hydantoin
|
Formaldehyde-releasing preservative | May be relevant to the new formaldehyde warning threshold |
|
Imidazolidinyl Urea
|
Formaldehyde-releasing preservative | May be relevant to the new formaldehyde warning threshold |
|
Diazolidinyl Urea
|
Formaldehyde-releasing preservative | May be relevant to the new formaldehyde warning threshold |
|
Quaternium-15
|
Formaldehyde-releasing preservative | May be relevant to the new formaldehyde warning threshold |
Important: this isn't a complete list of every ingredient prohibited or restricted under UK cosmetics legislation. It's a practical reference to the ingredient names most relevant to the 2026 changes covered in our salon guides.
And remember the crucial distinction: the formaldehyde-releasing preservatives above are included so you can recognise them when checking products.
Their presence does not mean the product contains a newly banned ingredient or automatically tell you whether the new 0.001% warning threshold is exceeded.
What to Do if Your Product Contains a Banned Ingredient
First, identify exactly which ingredient you've found and which regulatory change applies to it. The dates aren't the same for every ingredient.
If you’ve found TPO, for example, check when you bought the product and keep the product and batch info handy. Then you can look up the latest guidance for existing salon stock.
Don’t rely on a social media post or assume the rules for the EU or Northern Ireland are exactly the same as those in Great Britain.
If you’re not sure about a product, reach out to the manufacturer, Responsible Person, or your supplier and give them all the details they need to identify your exact product or batch.
For the wider picture, our UK cosmetics regulation 2026 overview explains what the changes mean for salon professionals and the different deadlines involved.
Where to Find Confirmed TPO-Free Products
If you’re swapping out gel products that contain TPO, look for options where the manufacturer or supplier has confirmed the formula is TPO-free and compliant for Great Britain.
At Salons Direct, you can shop professional nail products from established brands and check the individual product information before ordering.
Don’t assume a product is TPO-free just because “TPO” isn’t front and center on the bottle. Always check the product info or ask for confirmation if you’re not sure.
Related Products
FAQ: Reading INCI Lists for Banned Ingredients
What does TPO look like on an INCI list?
Look for Trimethylbenzoyl Diphenylphosphine Oxide. This is the INCI name associated with TPO, the photoinitiator affected by the 2026 GB cosmetics changes.
What is an INCI name?
An INCI name is a standardised name used to identify an ingredient in a cosmetic product. It means that the name printed in an ingredient list may be different from the abbreviation or everyday name commonly used when people discuss that ingredient.
How do I know if my nail product contains TPO?
Check the product's ingredient list for Trimethylbenzoyl Diphenylphosphine Oxide.
If you can't find the ingredient information, or aren't certain whether information online relates to your particular product, contact the manufacturer or supplier with your product and batch details.
Does an INCI list tell me whether a product is compliant?
Not necessarily. An INCI list can help you identify ingredients, but it doesn't tell you everything about a product's formulation, concentration, regulatory status or when that particular stock was placed on the market.
Think of it as a useful first check, rather than your only compliance tool.
Are formaldehyde-releasing preservatives banned?
The 2026 regulatory change discussed here is not a blanket ban on formaldehyde-releasing preservatives.
It changes the threshold at which relevant finished products containing formaldehyde-releasing preservatives must carry the warning “releases formaldehyde”, from 0.05% to 0.001%.
Is 4-MBC the same as TPO?
No. They are different ingredients and, importantly, have different 2026 transition dates in Great Britain.
CTPA gives 15 July 2026 and 14 January 2027 for 4-MBC, compared with 15 August 2026 and 14 February 2027 for the group of 16 CMR substances that includes TPO.
Make Ingredient Checks Part of Your Salon Routine
INCI lists can look intimidating at first, especially when you’re searching for something with a name like Trimethylbenzoyl Diphenylphosphine Oxide.
But you don't need to memorise every ingredient used in professional cosmetics.
Knowing where to find the ingredient list, which names to look for, and when to ask your supplier or manufacturer for more info makes checking your salon stock way more manageable.
Keep this guide handy when you’re reviewing your current products, and make it a habit to check product info before anything new hits your treatment area.
Regulatory guidance last checked: 11 September 2026. This article is intended as general information for salon professionals and does not constitute legal or regulatory advice.
