Can You Use Diaper Rash Cream as Sunscreen?

In this article: Can you use diaper rash cream as sunscreen? All moms love a good hack! Today’s topic is using diaper rash cream in other ways than intended – and whether that’s a good idea…

I’ve already talked about using a zinc oxide sunscreen for diaper rash, but what about the other way around? Can you use diaper cream as sunscreen, provided it contains zinc oxide (NOT petroleum jelly!!!) as an active ingredient?

In theory, yes. In reality, it’s best not to.

Here is why using a zinc oxide diaper rash cream as sunscreen may NOT be a good idea:

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1. Nano VS. non-nano zinc oxide

Zinc oxide comes in two main forms: nano and non-nano which refer to the zinc oxide particle size and whether it’s nano-sized or not. A nanoparticle is a particle so small that it’s measured in nanometers. Just how small? Each nanometer is one-billionth of a meter.

To show you the size of a nanoscale, according to the National Nanotechnology Initiative, a single human hair is roughly 80,000 – 100,000 nanometers wide, and a sheet of paper is approximately 100,000 nanometers thick. By definition, particles smaller than 100 nanometers are considered nano, and particles larger than 100 nanometers are considered non-nano.

Diaper rash creams are almost guaranteed to be made with non-nano zinc oxide which is thick and pasty white, whereas many sunscreens contain nano-sized zinc oxide that’s made specifically because it’s easier to apply and goes on clear. Nano-sized zinc is especially popular because it doesn’t leave white residue.

In terms of sun protection, both nano and non-nano zinc oxide provide coverage against UVA and UVB rays, although reducing zinc oxide to a certain range on the nanoscale seems to yield higher SPF (UVB protection).

As an isolated ingredient, zinc oxide has all the right qualities for blocking ultraviolet radiation. That said, there are many factors that come into play when ingredients for sunscreen formulations are considered, so regardless of the UV blocking abilities of zinc oxide in general, some zinc oxide formulations may be more suitable for sun protection than others.

2. Zinc oxide particle shape

Regardless of the particle size of zinc oxide, zinc oxide particles also come in different shapes. How they clump together and cover the surface area affects the ability of the mineral to filter UV rays. This, too, can impact the level of UVB and UVA protection from one zinc oxide formulation to another.

3. Photoreactivity

Lab studies show that zinc oxide can be photoreactive, in particular the smaller, nano-sized particles. Larger particles of zinc oxide appear to be much less affected by UV rays. A photoreactive substance may generate harmful free radicals when exposed to UV rays, which can lead to skin damage and skin cancer.

Nano-sized sunscreen-grade zinc oxide is generally coated with a chemical substance to reduce the potential for photoreactivity. This isn’t required for the larger particles (non-nano) since their size makes them more photostable.

If you use diaper rash cream as sunscreen that contains zinc oxide as an active ingredient and some of that zinc is nano-sized and not sun-optimized, meaning it’s lacking the appropriate surface coating to prevent the development of free radicals, there is an increased susceptibility to cell damage. Again, diaper creams are generally only made with non-nano zinc oxide, but it’s something to keep in mind.

4. Concentration of zinc oxide

Your diaper rash cream may or may not contain enough zinc oxide to provide sufficient protection from the sun’s radiation.

The higher the percentage of zinc oxide, the better the protection from harmful sun rays. For every 1% of zinc oxide you get 1.6 SPF units (20% = SPF 32; 25% = SPF 40, etc.). However, using more zinc oxide also makes the texture denser and harder to spread on the skin.

Experts recommend that mineral sunscreens based on zinc oxide should contain at least 10-15% of zinc oxide, ideally around 20%. The FDA allows maximum concentration of zinc oxide in over-the-counter sunscreen products up to 25%. (The same applies for diaper rash creams except for diaper rash ointment where up to 40% is permissible.)

You can see where your diaper rash cream stands in the zinc oxide content by looking at the back label. (But remember, even if the zinc concentration is within the range for an effective sunscreen, the diaper cream may still provide inadequate protection from the sun based on other factors.)

5. Inactive ingredients

What other ingredients in addition to the main ingredient zinc oxide does the diaper rash cream contain?

Zinc oxide sunscreens and diaper rash creams are made with a variety of ingredients. The way each product is formulated is specific for the purpose for which the product is intended.

Although in some situations you can swap a zinc oxide sunscreen for diaper cream, it doesn’t always successfully work the other way around because sunscreen is just a little more complex.

For example, some skincare ingredients don’t interact well with UV rays from the sun and can contribute to sunburn and skin damage – ingredients that fall in the phototoxic spectrum are unlikely to be used in sunscreen. But they could be part of a diaper rash cream formulation since UV radiation isn’t of concern with this kind of product. Even certain essential oils have phototoxic properties, although they are otherwise safe. Many citrus oils fall in this category.

Pro tip: If you’re ever tempted to use diaper cream as sunscreen, watch out for fish oil/cod liver oil in the ingredient list which could make for VERY UNPLEASANT after effects.

Should you use diaper rash cream as sunscreen?

Sunscreens are designed to provide protection from UV rays; diaper rash creams are not. Sunscreens are tested to determine their ability to filter UVB rays (SPF – sun protection factor); diaper rash creams do not undergo such testing. A zinc-oxide-based sunscreen and zinc oxide diaper rash cream aren’t automatically interchangeable, even if the concentration of zinc in both is identical.

The bottom line is, zinc oxide diaper rash creams can offer inadequate UV protection when used as sunscreen.

I’m all for using a zinc oxide sunscreen for diaper rash as long as the formulation is sensibly minimalistic and baby-safe, but I wouldn’t recommend using diaper rash cream as sunscreen.

On a similar note…

Can you use a zinc oxide diaper rash cream for sunburn???

This is considered safe, as long as the formulation doesn’t contain ingredients that are too harsh. As a general rule, the more simple the ingredient list, the better, and this is especially true for use on injured skin.

Zinc oxide forms a protective layer on the surface of the skin, keeping the skin hydrated and protected from irritants. Zinc oxide can be beneficial for the skin in many ways and is safe for sensitive skin and gentle enough even for baby’s delicate skin.