Does Sunscreen Expire?

When to replace your sunscreen

The flowers are blooming, the sun is setting later, and there’s a warm breeze in the air. You know what that means: Summer is coming.

With your skin’s favorite season right around the corner (hello, vitamin D), it’s time to start thinking about sun protection. While lotions and moisturizers can help soothe your skin after a day outside, if you want to avoid sun damage from the start, only one skincare product will do the trick: sunscreen.

But don’t pull out last year’s bottle of sunscreen just yet. Have you ever wondered about the shelf life of your sunblock?

Does Sunscreen Expire?

Turns out, sunscreen does expire.

The best sunscreens are made using active ingredients, which (unsurprisingly) don’t have an unlimited shelf life. Over time, the chemical compounds that make up these active ingredients start to degrade. As the compounds fall apart, your sunscreen becomes less effective.

This applies to every sun protectant out there, including both mineral and chemical sunscreens.

Mineral sunscreens — topical creams that sit on top of your skin and block out harmful UV rays — are made with ingredients like titanium dioxide and zinc oxide that can change texture and turn gritty over time. On the other hand, chemical sunscreens, which absorb directly into your skin, are made with active ingredients like avobenzone, octinoxate, and oxybenzone that will eventually oxidize, becoming liquidy once expired.

How Can You Find Your Sunscreen Expiration Date?

Like any beauty product regulated by the FDA, all sunscreen products must have an expiration date printed on the bottle. There is one exception, though: if stability tests show that the formulation will remain stable for at least three years, then it does not need to include an expiration date.

If your sunscreen does not have a printed expiration date, then you should consider it expired three years after the date of purchase. The good news is that most sunscreens that don’t print an expiration date do print a manufactured date… but only most.

So, what about those that don’t?

It’s a good idea to get into the habit of marking the date of purchase on your own products, especially if you know there isn’t one included otherwise. This helps you not only keep track of how long your products have been in your cabinet, but also how effective they will be for your skin.

How Long Does Sunscreen Usually Last?

Though the shelf life for many sun protectants is around three years, that doesn’t mean all of them last that long.

Chemical sunscreens often expire faster than mineral sunscreens do due to oxidation — but that doesn’t necessarily make one better than the other.

The quality of a sunscreen has nothing to do with its shelf life. Instead, it’s all about SPF. SPF (or sun protectant factor) measures how well a sunscreen protects your skin from UV rays. This includes both UVA rays, which are associated with premature aging, and UVB rays, which can cause sunburns and rashes.

The higher the SPF, the more protected your skin. That means that a sunscreen with SPF 50 will block out more UV rays than a sunscreen with an SPF 30. The right SPF level for you depends on how long you spend in direct sunlight and what activities you’re doing.

What Are Some Signs of Expired Sunscreen?

By now you know that sunscreen definitely expires and that it’s best to avoid using it after the expiration date. But there’s another important question to ask: what are some signs that your sunscreen is expiring?

If your sunblock doesn’t come with a printed expiration date and you forgot to write down the date of purchase when you got it, there are some signs you can use to help gauge the relative effectiveness of your sunscreen.

Change in Color

A sure sign that your chemical sunscreen has expired is when it begins to change color. Expired sunscreens often turn a dark shade of yellow or even brown as their active ingredients degrade.

But how do weaker ingredients change the sunscreen’s color? It’s all thanks to chemistry.

Chemical sunscreens are made with chemical compounds that oxidize (lose electrons) with age. As these compounds break down, they release new chemical byproducts that can cause chain reactions in your sunscreen product. One of these byproducts — <phenols — is responsible for the brown color of your expired sunscreen.

Change in Smell

Different from changes in color, which have everything to do with how active ingredients break down, changes in smell as sunscreen expires comes from bacterial growth.

Microorganisms are not out of the ordinary in sun protectants. The natural UV-protecting factors of many algae and cyanobacteria make them popular ingredients among dermatologists. But microbes are only a good thing in sunscreen when they’re supposed to be there.

Just like any skincare product, your sunscreen can become contaminated with bacteria. Germs hiding underneath your nails or in the bottom of your beach bag can make their way inside your bottle of sunscreen, multiplying from there until your product is full of them. If your sunscreen does become contaminated, you’ll likely notice a sour smell coming from the product.

Unlike ingredient breakdown, bacterial contamination can happen at any time to a sunscreen, regardless of expiration or purchase date. So pay attention to how your sunblock smells before you put it on.

Change in Texture

Chemical sunscreens often change color as they expire, and both chemical and mineral sunscreens are at risk of contamination from bacteria and other microorganisms. But what happens to mineral sunscreens?

As the active ingredients in mineral sunscreen degrade, the product can start to change texture.

Unlike how chemical sunscreens oxidize over time, mineral sunscreens do something called “precipitating” over time. In chemistry, precipitation refers to the formation of a solid during a chemical reaction. These little hard bits mix in with the liquid sunscreen, causing the once creamy solution to feel gritty.

But sometimes, expired sunscreens can go the other direction: they can become more liquid.

Mineral sunscreens are held together by an emulsifier that stabilizes the formulation. As this emulsifier breaks down, the ingredients can begin to separate from one another — specifically, the water-based ingredients and the oil-based ones. As the water and oil pull apart, the sunscreen may turn runny.

Can You Still Use Expired Sunscreen?

So, it turns out that the bottle of sunscreen tucked into the back of your bathroom cabinet has expired. What should you do?

According to general research, you should not use expired sunscreen.

There are two primary causes for expired sunscreen: either the active ingredients in the formula have broken down over time, or the product has become contaminated. In either case, this expired product is not one that you want to put on your skin.

Using expired sunscreen can have a lot of unwanted side effects for your skin, including breakouts, irritation, and allergic reactions. In some cases, expired sunscreen may even lead to skin infections. So don’t take the risk — get a new bottle of sunscreen.

Does Expired Sunscreen Still Work?

Expired sunscreen isn’t just bad for your skin: it’s less effective.

As the chemical compounds in your sunscreen break down over time, these active ingredients weaken. Without your SPF at its full capacity, harmful UV rays can break through the barrier of your sunblock, sinking into your skin and causing all sorts of problems.

The worst of the problems is the risk of skin cancer — too much sun exposure can actually damage the DNA in your skin cells, changing not just the look of your skin (anything from a raging sunburn to a group of sunspots) but its genetic makeup.

Damaged skin cells can’t function properly in your body, so while the idea of a tan might be nice, it’s not worth the risk to your skin.

The Bottom Line

We all love the feeling of direct sunlight on our skin, but unfortunately, our skin doesn’t feel the same way.

Too much sun exposure can harm your skin, which means sunscreen is a must. But it's not enough to just wear sunscreen — that sunscreen needs to work.

While selecting the right broad-spectrum sunscreen for your skin tone certainly helps, nothing can make a sunscreen effective after its expiration date. And your skin needs that protection: without it, you leave yourself vulnerable to harmful UV rays that can cause both surface-level and skin-deep damage.