Many readers and followers have been asking for my opinion surrounding third-party sunscreen testings. Iโve written about this very briefly in replies on Twitter and Instagram before but hereโs my full-length blog post on it.
Third-party sunscreen testings have their place but I think they need to be closely examined with a sceptical mind to determine whether each claim has merit. Not disbelief but aย rejection of judgment until sufficient evidence is examined.

Different UV test methods will give vastly different results. Sunscreens are sometimes falsely accused of not meeting labelled claims due to flawed testing methodologies. For example, Japan requires in vivoย ISO 24444 (SPF) & ISO 24442 (UVA) test methods for all products with sun protection. In other words, theyโre tested on humans. Most third-party tests opt for in vitro tests, which are done on plates because theyโre much cheaper and faster. According to many peer-reviewed studies, however, their results are unreliable due to a lack of repeatabilityย and correlation between the in vitro and in vivo data. Test the same sunscreen 10 times, and youโll get 10 vastly different results.
Itโs also very common for major brands to have regional products and formulas. Shiseido sunscreens sold in the US, Europe, and Asia, for example, all contain different ingredients (resulting in different UV protection) but have the same packaging, and near-identical product names. I often come across Chinese third-party online testing (and subsequently failing) sunscreens that are clearly made in China for the local Chinese market but will still list Japan as the productโs country of origin.
Another thing to consider is just because a third party decided to take it upon themselves to test sunscreens, doesnโt mean theyโre automatically more trustworthy or reliable.
Consumer Reports test sunscreens in the US but their evaluations are completely based on their own made-up methodology which for SPF testing involves applying sunscreens to backs and then soakย in a tub of water before exposing the areas to UV light. This is not how SPF testing is done.ย It could be argued that CR is simply replicating what could happen in real life (e.g. swimming) but skewing a testing procedure โ especially an established one โ to achieve a specific test result is terribleย science.
There has been a huge push in China in recent years to grow and expand its cosmetic industry. Creating a cloud of mistrust surrounding existing popular brands while proclaiming the Chinese government has the strictest standards when it comes to sunscreens may encourage their own citizens to try Chinese brands (and dissuade people from buying products from countries with economic or politicalย conflict).
Insuk Ahn from the Korea Institute of Dermatological Sciencesย seems reliable, but she is clearly working with Korean brandsย regarding all her tests and findings because the country has a lot at stake on a global scale. (The South Korean government is well-known to play a big role in supporting the major players in the cosmetic industry because it helps with the countryโs soft power.) Taking South Koreaโs very strict defamation law and her position (and experience) in the industry into account, I find it very difficult to believe that sheโs impartial or completely truthful.
Issues like how the third party obtained the sunscreen sample and how was it stored come into question as well.ย I find the sunscreen choices in a few third-party tests I came across peculiar since numerous products shown have been discontinued or repackaged for a couple of years already. Mixing fresh and very old testing samples will obviously skew results.
Which sunscreen is โbestโ or โmost protectiveโ is quite a personal thing โ your skin type, how your skin reacts to UV, where you live, your climate, and your activitiesย all come into play.ย A sunscreenโs overall formula (and how it feels on the skin) matters just as much as the UVA/UVB rating. Itโs a moot point whether sunscreen has superior UV protection or not if itโs heavy, greasy, or unpleasant. The best sunscreen is the one that youโll actually use correctly and generously daily โ whatever that may be.
Hi, excellent comment. I find it very difficult to rely on any third party reviews precisely for the reason you mentioned โ they are often influenced by motives fr removed from impartiality. For that matter honest consumer reviews are a lot more reliable, although recently there has been an influx of fake reviews on all sites, including Amazon. Thank you for your blog ang your site, as I said in one of my previous messages I often refer to your descriptions when I want to buy a Japanese product. You deserve more recognition
Thank you for your kind words.
Yes, I agree. I feel that reviews from those that have the same skin type, personal preferences, and living in the same climate as you would be far more helpful and relevant than any third-party testings.
Could you please answer this random question? Is 3300ๅ a reasonable price to ship a 1200ๅ, 100-page book (mook) from amazon jp to the US (i.e. 1200๏ปฟๅ + 2200ๅ ๏ปฟ้ ้ๆ)? The book is no longer in-print; I can only find another copy on mercari jp, and the total cost to ship is >4000ๅ by most proxies.
Amazon Japan ships internationally via DHL express, expensive but extremely fast and reliable. Books tend to be heavy and therefore expensive to ship.
Generally speaking, the more items you buy, the less shipping works out to be overall since the rate is calculated per kg. This is especially true if the other items are small and very lightweight. Youโll often find that shipping just increases by 100-200JPY for each additional item you add.
Thank you for your insight. Can I borrow your mercari account instead? I promise itโs G-rated material. ๐
Is there an official lab or organization in Japan that requires sunscreen manufacturers for UV testing before they are released into the market? Or do they also accept test results from other approved labs?
As far as I know, SPF and PA testings in Japan are either outsourced to third-party labs or done in-house.
Thank youโฆall the sunscreen tests on social media are exhausting. Itโs like a fancier version of when people used to plug active ingredients into the BASF sunscreen simulator to estimate protection. And itโs scummy that organizations are jumping on this trend for their own gain.
I think the best way to decide on a sunscreen is to read unbiased reviews (to make sure itโs not universally panned) and try it yourself and judge the performance. Thereโs sadly not an easier or fool proof way to find out whether it will work
Any content about how many sunscreens on the market are supposedly โfailing to meet SPF claimsโ is guaranteed to generate a large amount of traffic and therefore revenue. Iโve seen a few articles in Taiwan that clearly used BASF sunscreen simulator (their results are copy/pasted).
There is a way and that is by reading the package carefully and actually following the manufacturerโs advice/directions! Most people donโt bother to do either.
Well it is possible for some products to be shitty and not live up to their promises like a product claiming to be sebum resistant not actually being the case in reality. Thatโs where reading reviews and trying it yourself comes into place.
But yes, reading the package and following instructions is definitely very important lol and should be a givenโฆ
Very true! It should be a given but based on my casual observation (on my main site), most donโt bother.
I completely resonate with the last paragraph. Whatโs the point of having a super-protective sunscreen thatโs too greasy or tacky for everyday wear? Thank you for the post!
I often hear people say that they donโt care that if sunscreen feels greasy as long as itโs highly protective. They, however, forget (or donโt realise) that sunscreen also needs to stay put on the skin in order to be protective. If itโs sliding around or itโs transferring off, theyโre not going to get anywhere close to the labelled protection.
How do you determine whether a sunscreen is good for an outdoor hike? Are the Kose Suncut Perfect Gel or Essence sunscreens only for indoor use?
By reading the packaging. Sunscreens that are formulated for the outdoors/sports are explicitly stated on the packaging (in Japanese of course). No guessing or detective work necessary.
Hi G,
Thanks for this. Just wanted to check if KOKORO is still a good online option for Japanese products? I donโt want to go back to YesStyle now after seeing your post that it might be other formulas. I want the Japanese formulas (spfs specifically)
Thanks again.
I donโt know anything about them beyond what is said on their website.