For non-waterproof sunscreen, you can generally cleanse it with water or facial cleanser, and no special makeup removal is required. This has been said many times, but many people still have questions:
Why don’t you need to remove makeup?
Will sunscreen residue on the face cause skin problems?
…
Are these concerns warranted? Today we asked Dr. Han Yanfang from Yihe Medical Dermatology Department to talk about the topic of sun protection and cleansing.
- How much sunscreen is left before washing your face?
Before you use makeup remover to wash off your sunscreen, have you ever thought about how much sunscreen is left on your face?
Someone has done experiments. Whether it is organic sunscreen or inorganic sunscreen (physical sunscreen), within 10 minutes after application, the amount of sunscreen remains relatively stable; but in the subsequent 60 minutes, the inorganic sunscreen agent decreased by 50%, while the organic sunscreen agent decreased by 50%. Sunscreen was reduced by 70%.
The final experimental results showed that 8 hours after applying sunscreen, the dose of organic sunscreen was reduced by 75%, and the dose of inorganic sunscreen was reduced by about 65%.
This experiment illustrates two points:
If sun protection is strictly followed, regular reapplying is necessary;
For people who only apply it once a day before going out to work, there will be very little sunscreen left throughout the day.
This also tells us from the side that sunscreen is not as “unyielding” to us as we imagined.
- What is the cleaning effect of water, facial cleanser and makeup remover on sunscreen?
How to clean sunscreen? Let’s first look at some experimental data:
Study 1
For non-waterproof sunscreen, it is almost completely ineffective after being soaked in water for 20 minutes.
Study 2
In a study involving 20 participants, researchers compared the removal rates of sunscreen with water, facial cleanser (soap base), and cleansing oil.
Studies have found that using water + finger massage + towel drying can remove at least 40% of sunscreen (waterproof and non-waterproof); for non-waterproof sunscreen, if you use facial cleanser or makeup remover, 80% can be removed Above, the clearance rates for waterproof sunscreen are 63.2% and 94.2% respectively.
*It should be noted that in Study 2, only one brand of sunscreen (waterproof and non-waterproof), facial cleanser and cleansing oil were used, so this conclusion cannot represent the effects of all facial cleansers and cleansing oils. All sunscreen does.
However, since there are currently few studies on sunscreen cleaning methods, this study conclusion serves as one of the few references.
From Study 2, it can be found that cleansing with water can remove part of the sunscreen (but not very thoroughly), while for non-waterproof sunscreen, facial cleanser or cleansing oil is equally effective at removing it.
- What effects may cleansing oil and facial cleanser have on the skin?
As can be seen from the above, since the cleaning effect of the two on sunscreen is almost the same, what impact do facial cleansers and makeup removers have on the skin?
Then we have to start with the cleaning ingredient-surfactant.
Surfactant has both lipophilic (carries away greasy substances) and hydrophilic (dissolves in water) properties. One end of it “absorbs” grease or oily substances on the face, and the other end combines with water to clean the skin by washing the face. Purpose.
The main component of makeup remover is surfactant, and the principle is similar; makeup remover oil contains both oil and surfactant. The difference from makeup remover is that it has a water-in-oil structure.
Cleansing oil uses the principle of similar fusion to dissolve the oily substances on the surface of the skin, add water to emulsify it, and then rinse, thereby washing away the oily substances on the face. If the cosmetics on your face (such as oily makeup or waterproof sunscreen) are not easily removed with water or facial cleanser, you can use cleansing oil to clean them. Generally speaking, the oily base of cleansing oil is more suitable for dry skin, but not so friendly to oily skin.
Although there is currently no clear evidence that long-term use of cleansing oil and facial cleanser have a different impact on healthy skin, judging from the function of cleansing oil, it seems to be a bit “overkill” for cleaning non-waterproof sunscreen.
More importantly, for people who are not very skilled in using cleansing oil, it may be difficult to wash off the cleansing oil only by emulsifying it with water. At this time, they may use facial cleanser for “secondary cleansing”, which inadvertently causes excessive cleansing. Cleansing, if done too often, can damage the skin barrier.
Since it is impossible to soak in water for 20 minutes in our daily cleaning, in summary, if you want to clean the non-waterproof sunscreen more thoroughly, you can use ordinary facial cleanser to clean it; for the waterproof sunscreen, you can use makeup remover products to clean it.
- Do you really not have to worry about sunscreen residue on your face?
safety
Sunscreens are regulated as over-the-counter drugs (OTC) in the United States, and the production of sunscreens is also subject to the laws and regulations of various countries or regions.
Sunscreens undergo a number of tests before being put on the market, including analysis of potential harmfulness, local and systemic toxicity analysis on skin, cumulative toxicity of repeated use, skin sensitivity, mutagenicity, carcinogenicity and effects on the reproductive system. etc..
Regardless of strict layers of screening, don’t forget that the stratum corneum of our skin is a good barrier.
Not only can the skin effectively block the systemic absorption of sunscreen ingredients, it can also self-renew and shed, taking away surface residues. Even if the active sunscreen ingredients currently approved for use are absorbed by the body, the amount is very small, and no adverse effects on the human body have been found yet.
Therefore, for regular products, even if there is a little residue on the face, there is no need to worry too much about safety.
irritating
However, some people may still be worried about the local impact of sunscreen residue on the skin, such as whether it will cause acne, acne, etc.
So which ingredient in cosmetics can definitely cause acne? Unfortunately, the methods used to test the comedogenicity of products within the beauty industry vary widely, making it difficult to draw consistent conclusions; and products containing comedogenic ingredients do not necessarily cause acne even when applied to human skin.
To put it bluntly, it is not certain whether the residue of sunscreen is irritating to the skin, but the only thing that can be determined is that the most common impact of sunscreen on local skin is contact dermatitis, which is mostly caused by the fragrances and preservatives in sunscreen. In other words, this is a problem caused by the exposure, not a residual problem.
If you are concerned about this, it is recommended to choose products without fragrance and try them on a small scale first to observe whether there are any adverse reactions.
- How do you know whether sunscreen is “waterproof”?
There are many types of sunscreen formulations on the market. Depending on the emulsification system, they can be in the form of water-in-oil or oil-in-water.
Overall, products with an oil-in-water system are more popular in the market because they feel lighter and thinner on the skin. However, these products often have a lower sun protection factor and are easily washed away by water.
Products with a water-in-oil system tend to have a higher sun protection factor and have certain water-resistant and anti-sweat effects, but they are greasier and may not be so friendly to oily skin.
Although water-in-oil system products last relatively better in water environments or sweating conditions, the FDA has stated that in fact no sunscreen is truly “waterproof” because all sunscreens will eventually wash off.
Therefore, the FDA has corresponding SPF testing requirements for sunscreen products that claim to be water-resistant and anti-sweat. Those that can pass the test can be marked “water resistant” on the product.
In addition, the FDA also requires that such products should indicate the effective duration of a single application of sunscreen. For example, it should be applied once every 40 minutes when swimming, and once every 80 minutes if there is heavy sweating.
Therefore, even if you use “water resistant” sunscreen, you need to reapply it to ensure adequate protection if you sweat a lot or during swimming. This also shows that the stay of sunscreen on the skin is not as “stubborn” as imagined.
