Barrier creams: zinc oxide, petrolatum and what actually works

What a barrier actually does

It is worth being clear about the mechanism, because it changes how you use the product. A barrier cream does not heal skin, kill anything, or draw moisture out. It forms a water-repellent layer that stops urine, stool and moisture from reaching the skin surface. The skin then repairs itself, which it is very good at, given the chance.

Two consequences follow, and both are the opposite of what most people do:

• A thin, evenly rubbed-in layer is close to useless. If the cream has disappeared into the skin, there is no barrier left on top of it.
• You do not need to remove it at every change. Scrubbing cream off sore skin does more damage than leaving it on.

Zinc oxide

The most widely recommended barrier ingredient, and the one most pediatric guidance names first. It is a mineral that sits on the surface as an opaque white layer, is mildly astringent, and is not absorbed.

Concentration matters. Products range from around 10% up to 40%, and the label states it:

• Around 10 to 13% is a light everyday barrier, fine for prevention on healthy skin.
• Around 20 to 25% is the workhorse strength for an active rash and for overnight.
• 40% is a thick paste for badly broken skin, usually on a doctor's recommendation. It is difficult to remove and that is partly the point.

Pastes stay put better than creams and ointments, which is why they are used on the worst rashes and at night. They are also harder to spread on sore skin, so warming a little between your fingers first helps.

Petrolatum

Plain petroleum jelly. Cheap, extremely well tolerated, almost never causes a reaction, and forms an excellent occlusive barrier. It is the simplest option, and for prevention on skin that is not currently broken it is hard to beat on either performance or price.

Its limitation is that it is transparent, so it is harder to see whether you have applied enough, and it does not have the mild astringent effect of zinc on weepy skin. Many products combine the two, which is a sensible combination rather than a marketing one.

The other ingredients you will see

• Dimethicone. A silicone that forms a breathable water-repellent film. Lighter than zinc, non-greasy, well tolerated. A reasonable everyday preventive barrier.
• Lanolin. Derived from wool. Effective and moisturizing, but a more common cause of contact allergy than the others. Worth avoiding first if you suspect a reaction.
• Cod liver oil, calendula, chamomile, aloe, shea. Added for soothing or marketing reasons depending on the product. None of them are doing the barrier work. They are also more likely than zinc or petrolatum to be the thing a sensitive baby reacts to.
• Fragrance. No reason for it to be in a product applied to broken skin. Avoid it.

What to avoid

• Talcum powder. No longer recommended. It is an inhalation risk for babies and it does not treat a rash.
• Cornstarch and baking soda. Traditional remedies with no good evidence behind them. Starch can feed a yeast overgrowth, which is the specific rash you least want to make worse.
• Antiseptics and disinfectants. Harsh on already damaged skin.
• Steroid creams, unless a doctor has told you to. A mild steroid is sometimes the right treatment, prescribed and time-limited. Applied on your own under an occlusive diaper, which increases absorption, they can thin the skin. Never use a stronger steroid you have at home for something else.
• Antifungal creams "just in case". If it is yeast, you want the right treatment. If it is not, you have added an ingredient for no reason. Ask first.
• Anything with fragrance, or a "natural" product with a long botanical list, on skin that is already reacting to something.

How to apply it

1. Clean gently and let the skin dry

   Cream applied over damp skin traps the moisture underneath it, which is the opposite of the intention.

2. Apply thickly

   The standard is that you should still be able to see it on the skin afterwards. Frosting a cake is the usual comparison and it is a good one.

3. Cover everywhere the diaper touches

   Not only the visibly red part.

4. At every change

   And more thickly at the bedtime change.

5. Do not scrub it off

   Wipe away soiling, leave the clean cream in place, and add more on top.

6. Take it back to clean skin once a day

   Gently, with warm water and a soft cloth, and let the skin air before reapplying.

Most people under-apply. If a tube is lasting months on an active rash, it is not going on thickly enough.

Prevention versus treatment

For prevention on healthy skin, a light layer of petrolatum, dimethicone or a 10 to 13% zinc product at each change is plenty, and many babies do not need anything most of the time.

For an active rash, move to a 20 to 25% zinc paste, apply thickly at every change, and add air time.

For broken, weeping or bleeding skin, or a rash that has not improved in two to three days, the cream is no longer the question. Our guide to when to see a doctor covers what to do next.