Ingredient
Mineral oil
One of the most avoided ingredients in skincare, and one of the few the regulations permit to make up the entire product.
- INCI name
- Mineral Oil
- Also on labels as
- Paraffinum liquidum, Liquid paraffin, White mineral oil, Paraffin oil, Cosmetic grade mineral oil
- Found in
- cosmetics
Part of Eczema and atopic skin · Sensitive skin
Mineral oil is petroleum derived, and for a large number of people that sentence ends the discussion. It is worth not ending it there, because the regulatory position is unusually specific and it points the other way.
It is a drug active, and a permissive one
The skin protectant monograph permits “mineral oil, 50 to 100 percent”, and “30 to 35 percent in combination with colloidal oatmeal”.
Read the first number again. Up to 100 percent. The regulation contemplates a product that is nothing but mineral oil and treats that as an approved drug for protecting skin.
Very few ingredients are permitted to constitute the entire product. Petrolatum is another, at 30 to 100 percent. That is not a loophole; it reflects what these materials do, which is to sit on the surface and stop water leaving, and they do it better the less they are diluted.
The combination entry is worth noticing too: with Colloidal oatmeal the permitted concentration drops to 30 to 35 percent, because the two are doing complementary jobs and the monograph specifies the pairing rather than leaving it open.
The reputation, and where it comes from
The concern attached to mineral oil is contamination: polycyclic aromatic hydrocarbons and mineral oil aromatic hydrocarbons, which are genuinely associated with harm.
Those are found in untreated or mildly treated mineral oils, the industrial grades. The cosmetic and pharmaceutical grade is highly refined precisely to remove them, and it is the refined grade that appears in the monograph and in products.
So the honest statement is that the two things share a name and a starting material and differ in the step that matters. Treating a purified pharmaceutical excipient as though it were engine oil is the same reasoning error as the yoga mat argument about Azodicarbonamide: shared origin is not a fact about the dose in front of you. That argument is set out in the guide on hazard and exposure.
What it actually does, and does not
It is occlusive. It sits on the surface and slows water loss, which is why it works on very dry and compromised skin and why it is used after procedures and in nappy creams.
It is not absorbed to any meaningful extent, and the molecules are too large to pass the barrier in the way the “it clogs everything” account assumes. Its comedogenic reputation traces largely to ratings derived from rabbit ear assays, which is covered in the guide on what those ratings measure.
What it does not do is repair anything. It protects while the skin repairs itself. That distinction matters when choosing between it and something like Ceramides, which participate in the barrier rather than covering it.
Choosing between it and petrolatum
Both are occlusive, both are petroleum derived, both are monograph actives.
Petrolatum is the stronger occlusive and the heavier feel. Mineral oil is lighter and spreads more easily, which is why it appears in lotions where petrolatum would be unusable.
For very dry or eczema-prone skin the guidance is generally to use the heaviest thing you will actually tolerate, because the benefit tracks how consistently it is applied rather than how sophisticated the formula is. That is the argument on the eczema page.
Sources
- 21 CFR 347.10: Skin protectant active ingredients US Food and Drug Administration, via eCFR · ecfr.gov Permits mineral oil at 50 to 100 percent, and at 30 to 35 percent in combination with colloidal oatmeal, as a skin protectant active ingredient.
- 21 CFR 347.20: Permitted combinations of active ingredients US Food and Drug Administration, via eCFR · ecfr.gov Sets out which skin protectant actives may be combined and the labelling that applies to each combination.