Calamine

Calamine is one of the few things in a bathroom cupboard that most people could pick out of a line-up by colour alone, and one of the very few that is a drug active with a printed strength.

What it is permitted to do

The skin protectant monograph lists “Calamine, 1 to 25 percent” among the actives a product may use, and defines the whole category narrowly: a skin protectant drug product is “A drug product that temporarily protects injured or exposed skin or mucous membrane surfaces from harmful or annoying stimuli, and may help provide relief to such surfaces.”

That is a modest promise, and it is the promise. Nothing in the monograph lets a calamine product say it heals anything.

The regulator answers the obvious question sideways

Anyone reading the skin protectant list notices that calamine sits four entries above “Zinc oxide, 1 to 25 percent”, at an identical range, as though they were unrelated substances.

The answer is in a different part, written for anorectal products, and it is offhand about it. That regulation permits “Calamine, within a concentration range of 5 to 25 percent by weight per dosage unit (based on the zinc oxide content of calamine).”

That parenthesis is the most informative thing published about calamine’s composition in the whole of the regulation, and it arrives inside a bracket in a section about haemorrhoids.

Why the pink is not the point

What the regulation never does is define calamine. There is no section setting out what it is made of, no purity specification in the monograph, and nothing at all about the colour. The only compositional statement the regulator makes is the one inside that bracket, and it is about zinc oxide.

So the honest reading is narrow and worth having anyway: whatever else is in calamine, the dose is counted in zinc oxide, and the colour is not what the product is dosed on. A pink lotion and a white cream can be the same drug active at the same strength, and on the evidence published in the regulation the choice between them is cosmetic in the ordinary sense of the word.

Where it sits next to the rest of the list

The skin protectant list is unusual in how ordinary its members are: Petrolatum, Glycerin, Dimethicone, Colloidal oatmeal and Lanolin are all on it, and all of them appear in products that make no drug claim at all and therefore print no strength.

Calamine is the exception that mostly does make the claim, which is why it is one of the few of them you can read a number for. Which cosmetic ingredients are actually drugs covers the general case.