Does zinc oxide sunscreen expire?

Wearing facial sunscreen daily is the best way to protect human skin from sun damage. When headed outside for a full day in the sun, it's even more important to make sure you apply sunscreen. But you only have last year’s sunscreen in your bag and you’re wondering, does zinc oxide sunscreen expire?

In short, no. Zinc oxide sunscreen does not expire, because it contains the mineral compound zinc oxide, a solid inorganic substance of natural occurrence — in other words, sunshine does not change its molecular structure. It will always be effective against UVA and UVB rays, no matter how long the product that contains it sits on a shelf or in a hot garage.

 

The FDA

The Food and Drug Administration (FDA) requires all sunscreens remain at full strength for 3 years from purchase date, but that ruling was created because of petrochemical sunscreens, not physical sunscreens that use zinc oxide. True physical sunscreens contain either zinc oxide or titanium dioxide as their only active ingredient. Again, zinc oxide sunscreen does not expire and does not lose its ability to protect skin from UV rays.

Chemical vs Physical Sunscreens

The main difference between the two types of sunscreens is that physical sunscreen sits on top of the skin to reflect and absorb UVA and UVB rays, whereas chemical sunscreens absorb into skin and creep into our bloodstreams.

Chemical sunscreens apply smoothly, without leaving a thick film, using active ingredients such as oxybenzone, octinoxate, homosalate, octocrylene and avobenzone, which are created by extracting and processing various chemicals from crude oil. Such derived substances are known collectively as petrochemicals.

At best, petrochemical sunscreens exchange UV damage for toxic chemical damage. Unable to convert UV rays into harmless energy as well as mineral sunscreens, active petrochemical ingredients are actually photo-degraded by both UV energy and each other — breaking chemical bonds, disabling UV absorption capacity, and creating reactive free radicals in the body.

Also, additives in chemical sunscreen, such as emulsifiers, which help water and oil mix together, often break down sooner than other ingredients. You should never use a chemical sunscreen after the expiration date has passed.

Physical sunscreens utilize minerals zinc oxide or titanium dioxide as active ingredients. These sit on top of the skin where they absorb UV rays, convert them into infrared heat energy, then dispose of the heat away from the skin. They work immediately and do not seep into the skin like petrochemical products.

 

Photostablilty

Zinc oxide sunscreens are also photostable — which means their active ingredient (zinc oxide) does not deteriorate in sunshine. Zinc oxide does not change its molecular structure when exposed to UV radiation. As long as you “see” a physical sunscreen on your skin, it is doing its job. If you wipe off your zinc oxide sunscreen with a towel, you should reapply.

On the other hand, all the active ingredients in chemical sunscreens (avobenzone, oxybenzone, octisalate, octocrylene, homosalate or octinoxate) equickly degrade and stop protecting skin when exposed to UV rays. This is why the FDA requires sunscreen manufactures to tell consumers to reapply sunscreens frequently. Never use a chemical sunscreen after the expiration date has passed. And even if it hasn't expired, choose a good non-nano zinc oxide sunscreen instead.

 

Inactive Zinc Oxide Sunscreen Ingredients

In addition to zinc oxide, mineral sunscreens include other ingredients to allow us to spread the product on our skin. These other ingredients are called Inactive Ingredients and can spoil or separate. And although the zinc oxide sunscreen itself is still effective at keeping your skin safe, the inactive ingredients can eventually spoil.

 

Proper Zinc Oxide Sunscreen Storage

Because inactive ingredients in sunscreen can expire and even healthy oils like Vitamin E and olive oil can go stale, it is important to take care of your mineral sunscreens. We recommend keeping the stick/tube out of direct sunlight. Keep it in a cool, dark place.

 

Waxhead Zinc Oxide Sunscreen

All our sunscreens contain only non-nano zinc oxide as an active ingredient — and so they will never expire in the sense they will always protect your skin from UV rays. Our inactive ingredients are also resistant to oxidation, and zinc oxide acts as both an antimicrobial and anti-fungal preservative.

Our sunscreens still carry a 3-year expiration date (per the FDA), but know they will still protect your skin after the expiration date has passed.

 

 

Ask us anything!

Email Mac questions about sunscreen, skincare or anything outdoors > mac@gowaxhead.com