Petrolatum: the most studied moisturizer, and why some products skip it

Petrolatum has been on pharmacy shelves for well over a century, and it’s in more ointments, balms and healing creams than almost any other ingredient. It’s also one that a growing number of products proudly leave out. Both things can be true: it’s the most studied moisturizing ingredient we have, and some people have good reasons not to like it. Here’s the full picture.

What petrolatum is, and what it does on your skin

Petrolatum, also called petroleum jelly or white soft paraffin, is a semi-solid mix of hydrocarbons (molecules made of hydrogen and carbon) refined from petroleum. On the label it appears as “petrolatum” or “white petrolatum”.

It belongs to the family of moisturizing ingredients called occlusives. An occlusive doesn’t add water to your skin; it forms a thin, water-resistant film on the surface that slows water from evaporating out of it. Dermatologists measure that evaporation as transepidermal water loss, or TEWL.

Petrolatum is the strongest occlusive in common use. A 2016 review in the Indian Journal of Dermatology reports that at a concentration of just 5 per cent it reduces TEWL by more than 98 per cent, compared with roughly 20 to 30 per cent for lanolin, mineral oil or silicones. It works best on slightly damp skin, where the film traps the water that’s already there.

That is why it’s the go-to for the cracked, stinging skin of a Canadian February, when cold air outside and dry heat inside pull water out of your skin faster than a lotion can replace it.

What dermatologists use it for

The American Academy of Dermatology (AAD) lists five everyday uses for plain petroleum jelly:

• Relieving dry skin, including lips and eyelids, applied while the skin is still damp
• Helping minor cuts and scrapes heal by keeping the wound moist, which the AAD says helps prevent a large, deep or itchy scar
• Preventing chafing where skin rubs, for example on thighs during a run
• Treating diaper rash, applied at each change
• Rehydrating brittle nails between manicures

The wound-care use has unusually strong evidence behind it. In a 1996 randomized trial published in JAMA, 922 patients with 1,249 wounds from skin surgery were assigned to either plain white petrolatum or an antibiotic ointment. Infection rates were low and statistically similar in both groups, healing was the same at one, seven and 28 days, and the only allergic skin reactions occurred in the antibiotic group. The authors concluded that plain petrolatum is a safe, effective wound ointment.

For eczema, the itchy, inflamed skin condition also called atopic dermatitis, petrolatum-rich ointments are a mainstay because they hold water in without stinging. If a dry or eczema-prone patch isn’t better after two weeks of regular moisturizing, see your doctor or pharmacist.

Refined vs unrefined: the PAH question

This is the concern with the most substance behind it, so it deserves a careful answer. Crude petroleum contains polycyclic aromatic hydrocarbons, or PAHs, a group of compounds that includes known carcinogens. Unrefined or poorly refined petrolatum could carry them.

The petrolatum in cosmetics and medicines is not that material. It’s refined to pharmaceutical standards, and the refining is what removes the aromatic fraction. Germany’s Federal Institute for Risk Assessment (BfR) looked specifically at highly refined mineral oils and waxes, including petrolatum, in a 2018 opinion. It noted that under the EU cosmetics regulation these ingredients are only permitted when the full refining history is known and the starting material isn’t carcinogenic, and it concluded that no health risks are to be expected from applying such products to the skin, adding that no health effects had been reported despite daily use by many people over many years.

Health Canada’s position is similar. Its page on cosmetic ingredient safety says petrolatum’s safety has been reviewed by both the US FDA and Health Canada for its uses as a moisturizer and a skin protectant, that manufacturers must ensure ingredients susceptible to impurities are of good quality (pharmaceutical grade is given as the example), and that there have been no reports of unacceptable impurities such as PAHs in petrolatum in products it regulates.

So the honest summary is: the PAH concern is real for crude petroleum and theoretical for the refined ingredient in your ointment, provided the manufacturer follows the rules. Choosing products from makers who state they use pharmaceutical-grade (USP) petrolatum is a reasonable way to add confidence.

The acne myth

“Petroleum jelly clogs pores” is one of the most repeated claims in skin care, and the evidence doesn’t support it. The idea traces back to old rabbit-ear tests, a screening method where ingredients were applied to the inside of a rabbit’s ear to see if they produced blocked pores. Early petrolatum tests were positive, but the material was later found to be impure, and repeat testing did not show a comedogenic (pore-blocking) effect. A 2024 review in the Journal of the American Academy of Dermatology lists acne among the misconceptions about petrolatum that the evidence dispels.

Two caveats keep this balanced. First, petrolatum seals in whatever is under it, so if your face already carries sweat, sunscreen and a rich cream, a layer of petrolatum on top can make breakouts more likely even though it isn’t the direct cause. Second, the AAD still advises people who are acne-prone to keep it off their face. That’s cautious, practical advice rather than a verdict on the ingredient.

Why some people avoid it anyway

None of the above means you have to use it. People skip petrolatum for reasons that are worth respecting:

• Feel. It’s greasy, it doesn’t absorb, and it can leave marks on clothes and pillowcases. The 2016 review calls it one of the best moisturizers but “cosmetically less acceptable” for exactly this reason.
• Origin. It’s a petroleum product, and some people prefer plant-based ingredients on principle, whether for environmental reasons or personal ones.
• Ingredient philosophy. Some product lines are built around avoiding mineral-oil-derived ingredients, and some people want exactly that.
• It doesn’t add water. On its own, petrolatum doesn’t hydrate; it prevents loss. Skin that’s already very dry does better with a humectant (a water-attracting ingredient like glycerin) underneath, or with a formula that combines both.

Plant-based occlusives such as shea butter, beeswax and plant waxes do a similar job with a different feel, though generally with less complete water-loss reduction. If a petrolatum-free balm keeps your skin comfortable, that’s a perfectly good choice. You can compare balms and ointments reviewed by the Panel to see the range.

Allergy: about as low as it gets

One more point in petrolatum’s favour: it almost never causes allergic reactions. It’s so inert that dermatologists use it as the base for patch tests, the tests used to identify contact allergies. In the 1996 surgical trial, no patient using plain petrolatum developed allergic contact dermatitis. If a petrolatum-based product gives you a rash, the more likely culprits are other ingredients in the formula, such as fragrance or lanolin, and it’s worth a visit to your doctor or pharmacist to sort out which.

The bottom line: petrolatum is the best-documented occlusive in dermatology, backed by decades of use, controlled trials and reviews by Health Canada and European regulators. It’s excellent for very dry skin, healing scrapes and winter lips, and not a pore-clogger. Its main drawbacks are how it feels and where it comes from. If those matter to you, petrolatum-free balms exist and can work well; if they don’t, there’s no evidence-based reason to avoid it.