How Long Does Sunscreen Last Once Applied?

What Type of Sunscreen Should You Use?

To understand what sunscreen you should use, let’s look at what you need to protect yourself from. There are two types of sun rays - UVA and UVB.

UVA rays penetrate deeper layers of your skin. They can contribute to skin cancer, premature wrinkles, and aging of your skin. (1,2)

UVB rays also contribute to skin cancer, as well as damaging the top layers of your skin, and causing sunburn. (1,2)

It’s important to wear sunscreen if you're outside, even when it’s cloudy. UVB rays get stronger during the day and pose the biggest risk from late morning to mid-afternoon, whereas UVA rays maintain the same level of strength throughout daylight hours and all year round, even penetrating windows and clouds.(1,2)

When picking a sunscreen you should choose a broad-spectrum sunscreen. These protect against both UVA and UVB rays. (3)

What About Chemical and Mineral Sunscreens, which is best?

Chemical sunscreens contain ingredients that act as UV light blockers. They’re absorbed into the skin to help prevent sun damage.4,5

Mineral sunscreens sit on the surface of the skin, acting as a physical barrier to block harmful UV rays.4,5

Cetaphil Sunscreens provide broad-spectrum protection and include antioxidants, which can help protect your skin from surface free radicals - unstable molecules which in high quantities can contribute to aging, inflammation, and disease.6

As mineral sunscreens don’t need to be absorbed into your skin they can be applied as the final step in your skincare routine, after a moisturizer.

Cetaphil also has moisturizers that include chemical sunscreen, such as Cetaphil Daily Facial Moisturizer SPF 50, which is fragrance-free and contains vitamin E. If using a moisturizer with built-in SPF there is no need to add additional sunscreen after applying and this moisturizer can be applied before your make-up.

What Strength of Sunscreen is Best?

Higher SPF sunscreens are better at blocking harmful UV rays. SPF stands for Sun Protection Factor, and it measures how much UVB radiation is required to burn protected skin, compared to the amount required to burn unprotected skin. A sunscreen with SPF 15 blocks out 93% of UVB rays, SPF 30 blocks 97%, and SPF 50 blocks 98%.(1)

Broad-spectrum sunscreens also block out UVA rays. Two mineral ingredients included in sunscreens offer both UVA and UVB protection - these are zinc oxide and titanium dioxide. Cetaphil Sheer Mineral Sunscreens include one or both of these protective ingredients.

The best SPF for you will depend on your level of sun exposure. Dermatologists recommend that you use broad-spectrum sunscreens that are at least SPF 30,3 so it’s important you pick a sunscreen such as Cetaphil Sheer Mineral Sunscreen Broad Spectrum SPF 30* to meet these requirements. However, if you’re often out in the midday sun your risk of sunburn is higher than early morning or late afternoon, so a higher SPF will provide better protection if applied and reapplied correctly.(7)

You should also use more caution when you’re near water, snow, or sand because they reflect the sun’s rays, which increases your chance of getting sunburn.(3)

Can you use the same sunscreen on your face and body?

Your face, especially in delicate areas under your eyes, is more sensitive than other parts of your body and may require a sunscreen designed for sensitive skin.

How long does sunscreen last on your skin?

You may think that the higher the SPF, the longer you can stay out in the sun without reapplying sunscreen - but this isn’t true! Remember, the SPF of your sunscreen is not linked to how long you can stay in the sun, just to the amount of sun exposure you’re protected from.(7)

Regardless of SPF, the protection will begin to wear off after a few hours. The advice from experts, therefore, is to reapply sunscreen every two hours.(3,7)

How long does sunscreen last on your face if you have makeup on?

Some makeup, such as foundations, naturally offer a sun protection of around 3 or 4 SPF.(4) This is very low, so you’ll still need to wear sunscreen under your makeup if you’re going out into the sun. If your foundation includes a high SPF, you may have some more protection, but you should make sure your face is fully protected with sunscreen and you need to reapply sun protection to your face after two hours - just as you need to reapply to your body.

person blocking the sun from their face and body

Do You Need to Reapply Sunscreen After Swimming or Exercising?

Some sunscreens can be washed and rubbed away. Activities such as swimming and exercising (with lots of sweating) can wash away sunscreen. If you rub yourself dry with a towel then you can also rub away your sun protection, so you’ll need to reapply once you’ve finished swimming or exercising.(7)

Some sunscreens however are water-resistant. This means that your sunscreen is still effective, even after getting wet. Cetaphil Sheer Mineral Sunscreen Broad Spectrum SPF 50 is water-resistant for up to 80 minutes. This means that if you apply sunscreen and go swimming straight away, you’ll need to reapply your sunscreen 80 minutes later.

What is the Best Sunscreen for Your Skin Type?

It’s important to choose the best sunscreen for your skin. If you have fair skin it’s advised to use a stronger SPF because you’ll burn quicker than someone with a darker skin tone.7

If you have acne-prone skin then it’s important to choose a product that won’t clog your pores and if you have oily skin you should avoid greasy formulations.

Applying Sunscreen Correctly

In order for your sunscreen to protect you fully, you need to apply it correctly.

Firstly, you should use at least one ounce of sunscreen (roughly the amount to fill a shot glass) to cover your body from head to toe. This includes around half a teaspoon of sunscreen for your face and neck. Studies show that people generally apply around 20 - 50% of this amount — which means they’re not as protected as they think.(8)

Secondly, you should apply sunscreen before you go into the sun. Don’t wait until you’re already on the sun lounger! According to experts, you should apply chemical sunscreens around 15 minutes before you go outside into the sunshine. This is because it takes around 15 minutes for the sunscreen to absorb, ready to protect you.(3,7 )

When applying sunscreen don’t forget to cover the tops of your feet, the top of your head, your ears, and your lips. Stick sunscreens such as Cetaphil Sheer Mineral Sunscreen Stick Broad Spectrum SPF 50* are great for applying to these often-forgotten areas.

Sun Safety Tips

There are a few other tips you can follow to protect yourself in the sun:

Try to limit your exposure to the sun during peak hours.(7)
Wear a hat. Hats with a broad brim can help protect your face.(4,7)
Wear sunglasses to protect your eyes.(4,7)
Cover up bare skin with light clothing.(4,7)
Stay in the shade as often as you can.(3)

Bottom Line

Applying sunscreen is crucial for keeping you and your skin safe and healthy. Always make sure you’re applying enough in the first place and then reapply every two hours. Remember that harmful UVA and UVB rays are always there, even in the winter, so make sunscreen a part of your daily skincare routine, come rain or shine.

*Products only available in the US.

References

Dale Wilson B, Moon S, Armstrong F. Comprehensive review of ultraviolet radiation and the current status on sunscreens. J Clin Aesthet Dermatol. 2012;5(9):18-23.
UV Radiation and Your Skin. Skin Cancer Foundation. Available at https://www.skincancer.org/risk-factors/uv-radiation/. Accessed 22 November 2022.
Sunscreen FAQs. American Academy of Dermatology Association. Available at https://www.aad.org/media/stats-sunscreen Accessed 22 November 2022
Gabros S, Nessel TA, Zito PM. Sunscreens and Photoprotection. In: statpearls. NCBI bookshelf. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK537164/. Accessed November 22, 2022.
Keyes E, Werth VP, Brod B. Potential allergenicity of commonly sold high SPF broad spectrum sunscreens in the United States; from the perspective of patients with autoimmune skin disease. Int J Womens Dermatol. 2019;5(4):227-232. doi: 10.1016/j.ijwd.2019.05.006.
Pham-Huy LA, He H, Pham-Huy C. Free radicals, antioxidants in disease and health. Int J Biomed Sci. 2008;4(2):89-96.
Sunscreen: How to Help Protect Your Skin from the Sun. US Food and Drug Association (FDA). Available at: https://www.fda.gov/drugs/understanding-over-counter-medicines/sunscreen-how-help-protect-your-skin-sun. Accessed November 22, 2022.
Petersen B, Wulf HC. Application of sunscreen – theory and reality. Photodermatol Photoimmunol Photomed. 2014;30(2-3):96-101. doi: 10.1111/phpp.12099.