As a dermatologist, I am often asked about the best ways to protect our skin from the sun's harmful rays. With summer approaching and more time spent outdoors, it's important to understand the difference between water resistant SPF and regular SPF. Many people wonder if they need to reapply water resistant SPF after swimming or if it provides enough protection on its own. Let's dive into the truth about water resistant SPF and debunk some common myths.
The Basics of Water Resistant SPF
First, let's define what we mean by water resistant SPF.This type of sunscreen is designed to stay on the skin for a longer period of time, even when exposed to water or sweat. The SPF (sun protection factor) number indicates how long the sunscreen will protect your skin from UVB rays, which are responsible for causing sunburn. For example, an SPF 30 sunscreen will protect your skin for 30 times longer than if you were not wearing any sunscreen at all. Water resistant SPF is labeled as either "water resistant" or "very water resistant." The former means that the sunscreen will maintain its SPF level for 40 minutes while swimming or sweating, while the latter means it will maintain its level for 80 minutes. Keep in mind that these numbers are based on ideal conditions and may vary depending on how much you are sweating or how long you are in the water.
The Myth of Waterproof Sunscreen
Before we dive into whether or not you need to reapply water resistant SPF after swimming, let's address a common misconception: there is no such thing as waterproof sunscreen.The FDA has banned the use of the term "waterproof" on sunscreen labels, as it can be misleading. No sunscreen is completely impervious to water, and even water resistant SPF will eventually wear off. So why do we still see sunscreens labeled as "waterproof" or "sweatproof"? This is because the FDA allows the use of the term "water resistant" if the sunscreen has been tested and proven to maintain its SPF level for a certain amount of time while in water. However, it's important to remember that this does not mean the sunscreen is completely waterproof.
Do You Need to Reapply Water Resistant SPF After Swimming?
Now, let's get to the heart of the matter: do you need to reapply water resistant SPF after swimming? The short answer is yes. While water resistant sunscreen does provide longer protection than regular sunscreen, it is not a substitute for reapplying after swimming or sweating. According to the American Academy of Dermatology, you should reapply sunscreen every two hours, regardless of whether it is water resistant or not.This is because sunscreen can rub off or wear off over time, leaving your skin vulnerable to UV rays. Additionally, even if you are using a water resistant SPF, it may not provide enough protection if you are in the water for an extended period of time. It's also important to note that water resistant SPF only protects against UVB rays, not UVA rays. UVA rays are responsible for causing premature aging and can also contribute to skin cancer. Therefore, it's crucial to choose a broad-spectrum sunscreen that protects against both types of rays and to reapply regularly.
Tips for Proper Sunscreen Application
Now that we know the importance of reapplying sunscreen, here are some tips for proper application:- Apply sunscreen 15 minutes before going outside to allow it to fully absorb into the skin.
- Use at least one ounce (about a shot glass full) to cover your entire body.
- Reapply every two hours, or immediately after swimming or sweating.
- Don't forget to apply sunscreen to often overlooked areas such as the ears, back of the neck, and tops of the feet.
- Choose a broad-spectrum sunscreen with an SPF of 30 or higher.
The Bottom Line
In conclusion, while water resistant SPF does provide longer protection than regular sunscreen, it is not a substitute for reapplying after swimming or sweating.To ensure proper protection from both UVB and UVA rays, it's important to choose a broad-spectrum sunscreen and reapply every two hours. Don't be fooled by the term "water resistant" - always remember to reapply regularly for optimal sun protection.
