What "dermatologically tested" does and does not mean

Dermatologically tested is printed on cleansers, creams, wipes and shampoos, usually near hypoallergenic and clinically proven. It sounds like a standard. It is not one.

What it usually means

In the EU and the US there is no legal definition of dermatologically tested and no required protocol behind it. In practice it means the brand ran some form of skin compatibility test, often a patch test on a group of volunteers, and did not see enough irritation to stop them from using the phrase. The size of the group, the length of the test and the threshold for "enough" are up to the brand.

That is not nothing. A product that was tested on skin at all is better than one that was not. But two packs with the same phrase may sit behind very different tests, and you cannot tell them apart from the front.

The neighbours on the label

• Hypoallergenic has no legal definition either. It means the brand tried to leave out common allergens. It does not mean the product contains none.
• Clinically proven should point to a specific claim and a specific study. When it stands alone it points to nothing.
• Non-comedogenic means a test for pore-clogging was run, again with no shared standard.
• Fragrance-free, paraben-free, sulfate-free, silicone-free, alcohol-free are different. Each one is a statement about the ingredient list, and the list is printed on the same pack.

Why the list beats the front

The ingredient list is the one part of the label that is regulated everywhere: every ingredient, in order of amount, with the declared fragrance allergens named. A phrase on the front is marketing; the list on the back is the record. When they disagree, trust the back.

That is the whole idea behind Skincare Check. We do not rate a product's safety, and we do not repeat its front-of-pack promises. We read the list and answer six questions from it: vegan, fragrance-free, paraben-free, sulfate-free, silicone-free and alcohol-free. When the list cannot answer, we say not sure.

If your skin reacts easily

Dermatologically tested is a reasonable tie-breaker between two similar products. It is not a substitute for reading the list for the things your skin has reacted to before, and it is not a substitute for a patch test on your own arm.