You paid R$90 for a shampoo that says “for coloured hair”, used it for three weeks, and the colour faded at exactly the same rate as always. The front of the bottle talked about colour protection and argan oil. What it did not tell you is that the surfactant in the formula is the same one used in a R$12 shampoo, and that the argan oil sits fortieth on the list on the back, somewhere after the preservative.
That is not fraud. It is a division of labour. The front of the bottle is advertising and answers to marketing. The back is information and answers to cosmetic labelling rules, which in Brazil are set by Anvisa, the national health regulator. Two different documents glued to the same piece of glass, and only one of them is required to be accurate.
The rule nobody explains to the shopper
The ingredient list on a cosmetic is written in international nomenclature (INCI, for International Nomenclature of Cosmetic Ingredients), which is why water shows up as “Aqua” and vitamin B5 as “Panthenol”. And it follows one simple rule: descending order of concentration. The first name is whatever there is most of in the bottle. The last is whatever there is least of.
With one allowance that changes everything: below 1%, the order stops being mandatory. The manufacturer can list that final handful in any sequence it likes, and it usually chooses to start with the name that sells.
So the list has two halves with different legal status. The first half is an honest ranking. The second half is a shop window.
What usually sits in each position
For an ordinary mass-market shampoo, the distribution looks roughly like this:
| Position | What usually sits there | Approximate share |
|---|---|---|
| 1st | Water (Aqua) | 70% to 85% |
| 2nd to 4th | Surfactants: the part that cleans | 8% to 15% combined |
| 5th to 10th | Thickeners, pH adjusters, light conditioning agents | a few per cent |
| After the preservative | Everything the front of the bottle promises | a fraction of 1% |
In a conditioner the structure is similar, with second position taken by a cationic conditioning agent (Behentrimonium Chloride, Behentrimonium Methosulfate, Cetrimonium Chloride) and by a fatty alcohol such as Cetearyl Alcohol, which has nothing to do with the kind of alcohol that dries hair out.
The preservative is your ruler. Look for Phenoxyethanol, Sodium Benzoate, Potassium Sorbate, or any name ending in isothiazolinone. In most formulas these are used at fractions of 1%. Everything listed after them is, by definition, below that. If the hero ingredient from the advertising shows up down there, it is present, that much is true, and in a quantity that is enough to print on the label.
What the order alone will not tell you
Three perfectly legal manoeuvres distort the reading.
Water with a prettier name. When the first ingredient is “Aloe Barbadensis Leaf Juice” instead of Aqua, the bottle is still about 80% water: reconstituted aloe juice is water with a small fraction of solids. The front of the bottle then announces an “aloe vera base”.
Split surfactants. Instead of one surfactant at 12%, the formula uses three at 4% each. Each one drops a few places down the list, and the set looks gentler than it is. Add the surfactants up in your head rather than reading them one by one.
Pigment instead of active. In a purple shampoo, the violet appears as a colourant, with a four or five digit CI code, and almost always at the tail of the list. The intense colour of the liquid in the bottle says very little about how much pigment actually deposits. The closer to the end, the less pigment per wash, and the more washes it takes to change anything about your blonde.
The part where I disagree with you
The label reading that circulates online is a witch hunt: you learned to look for sulfates, silicones and parabens, and to put the bottle back on the shelf the moment you find one. That method turns the list into a blacklist, which is exactly why it fails.
The list is not a cast of villains. It is a ranking of quantities. A silicone in second position and the same silicone in thirtieth are two different products carrying the same name on the label.
Case by case:
Sulfates. Sodium Lauryl Sulfate and Sodium Laureth Sulfate are efficient detergents, and the second is considerably milder than the first. For coloured hair, the real problem is frequency and water temperature, not the existence of the molecule. And “sulfate free” does not mean gentle: it means the manufacturer used a different surfactant, which might be the very mild Sodium Cocoyl Isethionate, or a substitute that cleans poorly and leaves residue behind.
Silicones. Dimethicone does not penetrate the hair and does not ruin it. It sits on the surface, reduces friction, protects against heat, and comes off with an ordinary cleansing shampoo. What weighs hair down and builds up are the heavier, longer chains used in excess with no deep cleanse for weeks on end. Amodimethicone is often the more interesting one if you have colour: it has an affinity for damaged hair, which is precisely where the cuticle is open.
Hydrolysed proteins. Hydrolyzed Keratin, Hydrolyzed Wheat Protein. Here the size of the molecule decides whether it gets into the hair or just sits on the outside, and the label does not tell you the molecular weight. If the protein is listed after the preservative, the question about penetration is almost irrelevant: there is not enough of it there for the answer to matter.
What actually matters on the back, if you have colour
Four questions, in this order:
- What is the main surfactant, and in what position? This is the single
item with the most influence over what leaves your hair along with the lather.
- Is the pH declared? For coloured hair you want acidic. Few brands declare
it, and when they do it is a good sign. If it is not declared, the presence of Citric Acid on the list at least tells you somebody bothered to adjust it.
- Is there a cationic conditioning agent, and where? In a colour
maintenance shampoo, Polyquaternium or Guar Hydroxypropyltrimonium Chloride high on the list is worth more than any exotic oil at the tail.
- Is the hero ingredient before or after the preservative? That one
question rules out a good share of what you were about to buy.
When the label is not the issue
Reading labels solves product choice. It does not solve symptoms.
If you have itching that will not go away, flaking that comes back within days, patches of redness, pain in the scalp, sores, or hair loss that has clearly increased in volume, the shampoo label is the wrong conversation. That is a dermatologist appointment, and no change of bottle substitutes for one. The same goes for a reaction to a specific product: keep the packaging and take it to the doctor, because the ingredient list is exactly what they will want to see.
How to do this in two minutes, standing in the shop
Turn the bottle around. Read the first five names and stop. Then find the preservative and see what ended up behind it. If the reason you picked up that product is sitting in the second half of the list, you are paying for the front of the packaging.
No ingredient list can tell you whether a product is good for you. The label describes the formula, not your scalp, not the porosity of your hair, not the chemistry it has already been through. It is there to eliminate what makes no sense, and that alone narrows the shelf considerably.
If you would like to talk about your case
A home care kit comes out of a hair assessment, not out of a shop display. In the assessment, done with a trichoscope at the salon in Tatuapé, you follow the images on screen together with the professional: the state of your hair fibre and of your scalp. That picture is what decides what goes next to your sink, which products, in what order, and how often. It is usually fewer bottles than you own right now.
The assessment costs R$200 (Brazilian reais), credited in full towards the protocol. We measure again during or at the last session and compare with the image from the first day, at no extra cost.
We are in Tatuapé, in the East Zone of São Paulo, close to the Carrão and Tatuapé metro stations, open Tuesday to Saturday, 9am to 6pm, by appointment. Tuesday is the day reserved for scalp therapy. We can see you in English.