It is printed on thousands of products and almost nobody asks what it means. "Dermatologically tested." It reads like a verdict. It is a description of a procedure.
The phrase tells you that a test happened. It does not tell you what the test found.
There is no legal definition of it
Nothing in European or Swiss cosmetics law defines "dermatologically tested". No authority reviews it, signs it off or holds a register of products entitled to use it. A brand writes it because it did something it considers a dermatological test.
That is not the same as saying it means nothing. Under Article 20 of Regulation (EC) No 1223/2009, a claim must not imply a product has characteristics it does not have. Regulation (EU) No 655/2013 adds six common criteria that every claim has to meet, and the third one is evidential support: claims "shall be supported by adequate and verifiable evidence", taking into account state of the art practices.
So a brand printing the phrase must hold something. The regulation does not tell you what, and neither does the label.
It is one of four phrases, and they are not the same
The Commission's guidance on claim substantiation distinguishes four expressions that brands use once testing has been done: tolerance tested, tested under medical supervision, dermatologically tested, and clinically tested.
They sit on a spectrum. At one end, a test of whether skin tolerated the product. At the other, a study measuring whether the product did what it claims. They are printed in the same typeface and read as interchangeable, and they are not.
If a product says clinically tested and the claim is about hydration, it is telling you something specific. If it says dermatologically tested, it is telling you a dermatological test happened, and the sentence stops there.
What the report is supposed to contain
This is the part worth knowing, because it turns a vague phrase into a set of questions.
The Commission guidance sets out what a substantiation report should show. Among other things: the protocol, the product actually tested and its batch number, the number of volunteers and the justification for that number, their demographic information including skin type, the name and qualification of the person who carried it out, the results, and the signatures of the experts involved.
Read that list again and notice what a label cannot tell you. Whether the panel was twelve people or two hundred. Whether the test ran for two days or six weeks. Whether the product tested was the formulation now in the jar. Whether anyone reacted, and how many.
All of that exists somewhere in a file. None of it is on the front of the box.
What it never tells you
Even a well conducted test on a large panel is a statement about a group of strangers.
It does not tell you whether the product suits your skin. A tolerance test is designed to find out whether a product causes irritation in most people under controlled conditions. You are not most people, and your bathroom is not controlled conditions.
That is why a phrase on a box is a poor substitute for a fortnight of paying attention, which is the only method that produces an answer about you. We have written about how to do that, and about why the timing of a reaction tells you what kind of reaction it was.
What we are doing about it
We do not use the phrase, and we have not decided whether we ever will.
We have asked our manufacturer for the tolerance report itself rather than for permission to print the words. Our consulting pharmacist will assess it against the things listed above: which product was tested, under what protocol, on how many subjects, by whom, and what the results were.
If the report answers those questions, we will publish the answers rather than the phrase. The number of subjects, the protocol, the laboratory. If it does not answer them, we will say so and we will not print anything.
A claim that can only be made in two words is usually a claim that could not survive being written out in full.