How Long Does Sunscreen Last?
We all know it’s important to wear sunscreen. After all, too much sun can lead to premature aging and skin damage. It can also increase your risk of skin cancer.1 But what’s the best sunscreen to wear? How often should you reapply? And how do you apply sunscreen correctly? We’ve got the answers.
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.
UVB rays also contribute to skin cancer, as well as damaging the top layers of your skin, and causing sunburn.
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.
When picking a sunscreen you should choose a broad-spectrum sunscreen. These protect against both UVA and UVB rays.
濕疹成因有哪些？
Chemical sunscreens contain ingredients that act as UV light blockers. They’re absorbed into the skin to help prevent sun damage.
Mineral sunscreens sit on the surface of the skin, acting as a physical barrier to block harmful UV rays.
Cetaphil Sheer Mineral 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.
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.
最常見的濕疹部位
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%.
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.
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.
七大濕疹類型
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.
Sunscreens for the face are often a lighter consistency with a matte finish, so they can be worn under makeup, like Cetaphil Sheer Mineral Sunscreen Face Liquid Broad-Spectrum SPF 50*.
異位性皮膚炎是成人和兒童最常見的濕疹類型，通常由出生至半歲期間開始出現，症狀主要為皮膚乾燥，並出現感到疼痛及痕癢的皮疹。
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.
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.
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.
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.
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.
常見於中年人士，主要症狀是皮膚出現圓形斑塊。
這種濕疹的特徵是皮膚出現紫色或紅色斑塊且痕癢，當您放鬆或躺在床上時，痕癢可能會變得更加嚴重。
這種濕疹僅出現於腿部，是由於血液循環不良所引致的。血液積聚在腳踝和小腿的皮膚下，導致皮膚敏感紅腫、痕癢及出現鳞屑。
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.
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.
All Cetaphil Sheer Mineral Sunscreens are suitable for sensitive skin. Cetaphil moisturizers with chemical sunscreen are also available for different skin types, such as Cetaphil DermaControl Oil Absorbing Moisturizer SPF 30 for oily, sensitive skin, and Cetaphil Daily Facial Moisturizer SPF 15, which is suitable for dry to sensitive skin.
定期及於沐浴後為皮膚保濕，可以選用例如Cetaphil舒特膚倍加護醫學濕疹配方 – 潤膚霜等產品，不僅可以滋潤肌膚，臨床證實更有助修復受損的肌膚屏障。建議有濕疹傾向的人士，在肌膚微濕時使用不含香料的保濕霜，這樣更有助鎖住皮膚水分。
將防曬霜為您日常護膚程序的其中一部分，以保護您的皮膚免受陽光傷害或被紫外線進一步損害皮膚屏障功能。
應用溫水沐浴，並將時間縮短為5至10分鐘。較短的沐浴時間能幫助皮膚補水，並洗走硬皮、鱗屑、細菌或刺激物。2建議使用性質溫和的沐浴露，如Cetaphil舒特膚倍加護醫學濕疹配方 – 潔膚露，乳霜狀的潔膚露有助舒緩肌膚，並修復肌膚屏障。
要抵抗抓癢的衝動，因抓癢不但會令病情惡化，更可能會造成傷口，並導致感染。相反，應使用有助於緩解濕疹痕癢的產品。
Applying sunscreen correctly
以下是一些有關濕疹最常見的問題與答案。
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.
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.
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.
答：有可能，但每個人的情況不盡相同。雖然許多兒童的濕疹會隨著年齡的增長而消失，但在成年後可能會再次出現。濕疹亦可能出現在成人身上，惟不像兒童階段那麼常見。
答：濕疹暫時沒有根治的方法，但透過避免接觸誘發因素、需要時使用醫生的處方藥物、保持良好的護膚習慣，以及使用專門針對濕疹護理的產品，都有助控制症狀。
答：了解您誘發濕疹的成因最為重要，這樣就可以控制某些症狀，並減少濕疹發作的次數，但難以完全預防或避免所有濕疹類型復發。
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.
- Wear a hat. Hats with a broad brim can help protect your face.
- Wear sunglasses to protect your eyes.
- Cover up bare skin with light clothing.
- Stay in the shade as often as you can.
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.
