Why you should be using a retinoid
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I have a confusion about retinoids that I haven't been able to find an answer to:
If retinoids are approximately vitamin A, does this just mean that the average person is very vitamin A deficient? Should they just be eating vitamin A instead? (The best source is probably animal liver.) Surely this would have not just the beneficial skin effects but also lots of other positive effects on the body (surely facial skin is not the only part of the body bottlenecked by vitamin A).
I wonder if people who eat/absorb lots of vitamin A don't get any marginal benefit from retinoids.
Btw I'll pay $30 for a satisfying answer to this
Clarification: By vitamin A, I literally mean vitamin A. The compound that can be used without conversion. For example, the compound that is consumed through animal sources like liver.
Interesting question! I hypothesize the following:
Vitamin A is distributed throughout the body, so only a small amount actually benefits the skin. The body tightly regulates how much retinol is converted into retinoic acid, meaning that even if you consume a lot of vitamin A, your skin won't necessarily receive much retinoic acid. Topical retinoids, on the other hand, deliver a concentrated dose directly to the skin, providing targeted benefits that dietary vitamin A alone can't achieve. Even people with sufficient vitamin A levels in their bodies can still see significant skin improvements from topical retinoids due to their localized effectiveness. Also, consuming large amounts of vitamin A for additional benefits isn't advisable due to the risk of toxicity.
As a crude comparison, just drinking water doesn't automatically give you well-hydrated skin, while a moisturizer directly targets your skin's hydration.
When you say vitamin A, do you literally mean vitamin A, or the similar potential-precursor compound found in plants that is often mistaken as vitamin A? See my other comment.
My (34) skin has just now started to look aged. In response to that and migraines (linked to magnesium deficiency), I've started eating liver a lot. I'll report back in a year.
edit: I totally forgot I was doing this and started with retinol lmao
Dietary vitamin A (beta carotene) is not the active form of vitamin A (retinoic acid), it needs to be converted into the active form by the body's enzymes. Once retinoic acid is formed, it can bind to the retinoic acid receptor and regulate gene expression.
Retinoid treatment bypasses these enzymes and directly activates retinoic acid receptor signaling. So, eating vitamin A in the form of beta carotene won't directly increase retinoic acid receptor signaling because the rate-limiting step is the enzymes, but retinoid treatment will. This is also why you can't overdose on vitamin A by eating carrots.
Does this meet your criteria for a good answer? If not I can explain in more detail.
Hi, thanks for responding. You say:
Dietary vitamin A (beta carotene) is not the active form of vitamin A (retinoic acid), it needs to be converted into the active form by the body's enzymes.
It is possible to eat the active form of vitamin A, for example through animal sources like liver.
When I said vitamin A, I meant vitamin A (not the compound in plants that can be lossily converted into vitamin A).
So this doesn't answer the question IMO
The highly active form of vitamin A is isotretinoin, which you can take orally. It has substantial side effects though, meaning it's generally only used for severe (cystic) acne.
If you want to think of it as a kind of deficiency you can, but then only your skin is deficient in vitamin A (not the rest of your body).
This is not a good post. I knew that as soon as I saw the title, because there are several different "retinoids" that are very different. Most of them have side effects and a mechanism of action that indicates negative long-term effects. Also some are teratogens. Maybe just read the wikipedia pages for the individual compounds.
The post specifically mentions adapalene which works by "increasing cell turnover" which long-term is presumably a bad thing. It also reduces "keratinocyte differentiation and decrease keratin deposition" which makes skin more fragile, and it increases sensitivity to UV light.
"not a good post" sounds kind of harsh and hostile to me, FWIW.
Leaving out major differences and understating risks is a big problem. But I personally had absolutely no idea that there was even a potential for anything to be remotely this effective for skincare, with or without risks.
Thus, this post is highly valuable for me; and of course I'd do a little research before embarking on something this time-consuming and expensive (daily time cost isn't the right way to think about it; 10 minutes per day is about 60 hours per year, a week and a half of "full time" work devoted to looking younger every year)
I would prefer the author edit the post to say "there are differences and risks with each, do your due diligence and report back if you want". But I am still upvoting the post for giving me one solid rationalist clue about the massively complex world of skincare claims.
"not a good post" sounds kind of harsh and hostile to me, FWIW.
OK, how about this then:
I have certain standards for giving many people strongly-worded medical advice, and this post is not even close to meeting them. It tells people to do something they most likely shouldn't, based on brief and shallow research, and provides incomplete information. As such, I consider it unethical and it calls the judgement of the author into question in general.
Is that better?
If the post was just like, "hey, retinoids exist, if you have specific skin issues X or Y (keratosis pilaris, etc) you should consider them, especially the 3rd-generation ones like adapalene, note these side effects and check these articles and then maybe talk to your doctor" - that would be a good post. This is not.
IMO, I am not a huge fan of increasing the burden of evidence for medical claims one way or another. If the author believes that all things considered it's better for most people to use a retinoid, then I think the post title seems good. If the author doesn't believe that, then the title would be bad.
I don't think you improve people's decision-making in higher-stakes domains by reducing the amount of conversation and information sharing that happens around those topics (though it seems to be a common attractor in norm-space, which I find frustrating, and in as much as I get to set culture on LessWrong about how to handle topics that are often treated this way, I want to put an explicit flag up around "no, it's fine to openly share advice about high-stakes domains, indeed we probably want to subsidize information sharing about high-stakes domains").
Yeah, actually that sounds way better to me. It's not only nicer but more informative. You really think people shouldn't be using retinoids, based on your read (it's more than mine) of the literature?
I really think most people shouldn't be using retinoids, especially not "retinoids in general". For people who have certain skin problems, certain retinoids can be worthwhile, but it's up to them if the side effects are worth the potential (mainly aesthetic) benefits.
I certainly wouldn't recommend "retinoids" - I'd talk about individual compounds.
My skin is starting to have the problem of looking way older than I'd like :) At the cost of sounding shallow, looks matter for a variety of purposes, so I'd take some measured risks and downsides to get the massive improvements shown in the photos here. I'll do some research if I get around to it before the singularity :) and report it in a comment on this post if I do anything worthwhile.
I somehow doubt anyone is going to read this and immediately slather a mixture of every retinoid known to man directly to their face (including many which are only available by prescription). If they did, I honestly wouldn't blame this post. They're going to either go to a doctor to find out more about prescription treatments, or Google "retinoid cream" and find some over-the-counter retinol that's safe and has no substantial side effects for most people. This is a perfectly OK introductory post.
I asked my dermatologist about skincare routines, and she said, approximately, “There is a cheap, widely available, extremely effective treatment for skin aging that has been around for decades”
I’ve read the article and notice that all the negative side-effects listed are due to issues with oral Retinoids rather than topical Retinoids.
Several of the articles I’ve read indicate that topical retinoids actually DECREASE the risk of cancer, though I agree this is confusing since they supposedly increase cell turnover rates, which should theoretically cause more mitosis-induced mutations to occur. But Retinoids are actually frequently used as anti-cancer drugs.
Google’s AI summarizer says you the mechanism of action is promotion of cell differentiation and inhibiting the progression of pre-malignant cells to malignant cells.
It also reduces "keratinocyte differentiation and decrease keratin deposition" which makes skin more fragile, and it increases sensitivity to UV light.
This is correct of course and why I specifically recommend in the post that people wear sunscreen when using retinoids.
I’ve read the article and notice that all the negative side-effects listed are due to issues with oral Retinoids rather than topical Retinoids.
No. Topical adapalene has side effects. Also, not sure why you're capitalizing retinoids.
But Retinoids are actually frequently used as anti-cancer drugs
Anti-cancer drugs generally increase the risk of developing cancer. Cancer preventing compounds reduce the risk of developing cancer.
This is correct of course and why I specifically recommend in the post that people wear sunscreen when using retinoids.
Most sunscreens contain compounds that absorb UV by breaking into radicals, which can then cause problems in cells. They also often contain endocrine disruptors. These aren't unavoidable issues but they are common. Sunscreen is also somewhat inconvenient.
No. Topical adapalene has side effects. Also, not sure why you're capitalizing retinoids.
I just checked 5 of the individual wiki pages linked from the retinoid page. You suggest they have side effects (together with their mechanisms of action) that "[indicate] negative long-term effects".
None of the linked pages' listed topical side effects indicated that to me. Here is the section on side effects for adapalene:
Of the three topical retinoids, adapalene is often regarded as the best tolerated. It can cause mild adverse effects such as photosensitivity, irritation, redness, dryness, itching, and burning, and 1% to 10% of users experience a brief sensation of warmth or stinging, as well as dry skin, peeling and redness during the first two to four weeks using the medication. These effects are considered mild and usually decrease over time. Serious allergic reactions are rare.
Pregnancy & lactation
Use of topical adapalene in pregnancy has not been well studied but has a theoretical risk of retinoid embryopathy. Thus far, there is no evidence that the cream causes problems in the baby if used during pregnancy. Use is at the consumer's own risk.
Topical adapalene has poor systemic absorption and results in low blood levels (less than 0.025 mcg/L) even after long term use, suggesting that there is low risk of harm for a nursing infant. However, it is recommended that the topical medication should not be applied to the nipple or any other area that may come into direct contact with the infant's skin.
What in here indicates negative long-term effects?
Adapalene is used topically. Wikipedia doesn't list skin fragility as a side effect but - as you can guess from its mechanism - it is one.
And the mechanism involves increased cell turnover, which long-term tends to either increase stem cell depletion or increase cancer risk. There's a tradeoff, which is why people don't just do the thing normally. Maybe your natural tradeoff is wrong and you want to adjust it, but you have to recognize that it exists.
1Can you link to a source about the increased cancer risk? Every source I've seen on this subject indicates retinoids DECREASE cancer risk, though I agree with you that this doesn't make much intuitive sense.
Highlighting the existence of different retinoids is good. I have used retinol serums and a tretinoin cream (not at the same time). Retinol products are the most popular in the retinoid skincare category, and are sold over the counter, so reading specifically about them might be worthwhile.
After checking out Melissa55’s YouTube channel, probably worth noting she was on HRT from her 40s until recently, so that might confound the retinoids effect for her in particular.
Anecdotally*, IPL/laser therapy seems to do all of these except increasing dermal capillaries, which it instead reduces. This makes it ideal for people with rosacea or other inflammatory problems, and fair skin (which often accompanies these problems).
*And with a few references: Effective treatment of rosacea using intense pulsed light systems - PubMed (nih.gov)
IPL irradiation rejuvenates skin collagen via the bidirectional regulation of MMP-1 and TGF-β1 mediated by MAPKs in fibroblasts - PubMed (nih.gov)
some studies find no significant effect on collagen etc.; I don't know what went wrong here besides perhaps too-tan skin: Intense pulsed light photorejuvenation: a histological and immunohistochemical evaluation - PubMed (nih.gov)
Also, sunscreen has substantial anti-aging benefits of its own so it’s a good idea anyways.
The human body uses the amount of UV light it gets to decide how much of the sex hormones to produce.
I notice substantial positive effects from my habit of getting 20 to 30 minutes of strong sun on my bare arms and legs and eyes every other day. The main positive effect is to make me more optimistic and maybe willing to expend effort and endure suffering in pursuit of my goals. (Naturally I avoid getting more UV than I need to keep my sex-hormone levels high.)
People on this site tend to be too dismissive of seemingly-mild interventions like sunlight. "If the goal is to raise the levels of the sex hormones, why not inject the hormones directly?" they might say. Well, I injected testosterone for a couple of years (decades before I started the habit I just described), and I prefer the effects of the sunlight habit I just described to the effects of injected testosterone. The injected testosterone got me into at least one physical altercation and made me expend much too much time and mental energy in the focused intellectual pursuit I was interested in at the time (programming-language design) and had other negative effects (on general metabolism) that are hard to describe.
Most interventions available to us into the functioning of the central nervous system are too strong in my experience, and injected testosterone's effect on me was too strong. I have a simple model of the brain or at least that part of the brain that controls physiology and mood as consisting of dozens of interlocking feedback loops, and things like injected testosterone alter the equilibrium of too many of the loops too strongly.
Maybe a person wearing sunscreen or high-SPF clothing that covers their arms and legs can get enough UV light to keep sex-hormone levels high through the eyes (as long as they're not wearing sunglasses) but if so, it would require spending at least 2 or 3 times more time in the sun, which makes it less convenient to maintain a habit of UV exposure to keep sex hormones high.
Note that this is a reply to myself.
Since the comment I am replying to is being upvoted, I will put a little more effort into explaining. "Getting 20 to 30 minutes of strong sun on my bare arms and legs and eyes every other day" is from neuroscientist Andrew Huberman. This effect of UVB light on the sex hormones seems to have been recently discovered; more information here.
That's an interesting paper! Although it seems a bit confounded - "Because eyes of mice and of human volunteers were not covered, we cannot exclude the possibility that solar/UV radiation to the eye affected the observed sexual behavior." Which would be interesting if true, suggesting that just being outside and getting UV light in the eyes would be the thing to do. I guess you note this at the end of your first comment.
What do you think about the potential skin aging effects of UV vs the potential health benefits?
https://www.sciencedirect.com/science/article/pii/S1015958423001392 suggests that bright light might be causing the effect, not UV.
Anyone else getting "ask your doctor if Photoshop™ is right for you" vibes from some of those before & after photos?
Hi Gene! As a fellow research-based skincare enthusiast, I’m thrilled to see this discussion here.
I've been using adapalene for about two years now, and I've experienced all the benefits it's known for: a dramatic improvement in my skin texture, brightness, and acne.
Adding to the sun protection advice, I think this point is so often emphasized in conjunction with retinoids because reversing signs of skin aging is a major motivation for people using them, and UV radiation is a major factor in breaking down collagen and elastin, accounting for up to 80% of skin aging — this figure is cited by both the Skin Cancer Foundation and the American Academy of Dermatology. While retinoids can help reverse some sun damage, it's smart to prevent the primary cause of degradation in the first place. In addition to sun avoidance, I highly recommend Korean sunscreens for their advanced cosmetic technology and comfortable textures, and many of them are very reasonably priced.
Thanks for the second expert opinion.
I don't suppose you've looked into the health risks (cancer and whatever else) of either retinoids or sunscreens? I'd want to know before embarking on a daily routine of either one.
Oh, I'm no expert! Just a skincare nerd who loves research-based information. I apologize if my wording was confusing.
I'm not quite sure why there's so much concern in the comments. Yes, oral retinoids, such as Accutane, do carry significant health risks for humans, but that's not the focus of this post. While high doses of oral retinoids have been associated with an increased risk of cancer in some animal studies, these studies typically involve doses much higher than those used in topical treatments.
When it comes to topical use, only trace amounts are absorbed, with adapalene having the lowest (<0.25 ng/mL). I tried really hard to find evidence of health concerns associated with topical retinoids, but they seem to be limited to skin irritation and a small potential risk of birth defects during pregnancy. In my opinion, adapalene is the best overall - it's more accessible, less irritating, has additional anti-inflammatory benefits, and is more chemically stable than tretinoin while offering comparable results.
As for sunscreen, you've opened up a whole can of worms there, haha! I'd recommend checking out Dr Michelle Wong, aka Lab Muffin Beauty, who is a fantastic cosmetic chemist with great knowledge on myths like hormone disruption and on retinoids as well. You can find her at https://labmuffin.com/ or on YouTube. I can imagine you're a busy man. If you have specific questions and my comment gives you a good feeling about my standards, feel free to ask – I'd be happy to look them up for you.
But to quickly summarize, there's tons of misinformation out there about the dangers of sunscreens that's not at all in line with the scientific consensus, made worse in the recent years by the "clean beauty" marketing / corporate opportunism movement. Sunscreens are rigorously tested and have huge safety margins (at least 100 times higher than the No Observed Adverse Effect Level or NOAEL), which take into account absorption through the skin and potential endocrine and other long-term effects.
Lastly, you shouldn’t use Retinoids if you’re pregnant or likely to become pregnant.
This needs more emphasis. Retinoid signaling is very important for embryonic development, so excess retinoids will really mess up your baby.
Sharing my experience here:
- VERY white skin, prone to dryness.
- Had been on a cleanser+moisturizer combo before going to sleep for most of my adult life. Very liberal use of sunscreen.
- Came across some research on different retinoids, started with a medium strength retinol serum (The Ordinary 0.5% Retinol Serum in Squalane) before moving to a higher strength retinol serum (The Ordinary 1% Retinol Serum in Squalane). Three drops on a dry skin after using a cleanser, one to each cheek, one to my forehead, spread evenly. Moisturizer applied after letting it settle for around 10 minutes.
- I chose a cheap product ($9.99) because by default I'm quite distrustful of the beauty industry, and assume that simple and cheap is probably good as long as it has the active ingredient that I want.
- I chose to start with the 0.5% strength and not the 0.25% for the same reason. My skin was kind of irritated for the first few days, but could handle 0.5% just fine. I moved to 1% in around 1.5 months after using 0.5% daily.
- I chose a cheap product ($9.99) because by default I'm quite distrustful of the beauty industry, and assume that simple and cheap is probably good as long as it has the active ingredient that I want.
- After roughly six months of using a retinol serum, I moved to a prescription tretinoin cream. Retinol already had quite a big effect, and I'm not sure using tretinoin is that big of an additional difference, at least for me. I do find using a cream easier than a serum, though.
I tend to favour simple and cheap products that have an active ingredient that have at least some amount of research backing up its effectiveness, and that are often recommended by dermatologists. Fancier and expensive products seem like snake oil to me, but I could be wrong on this. My intuition is that less products and less chemicals on your face is probably better than more, and I am quite suspicious of the lengthy multi-step regimens some people subscribe to.
I currently use the following:
- Before going to bed:
- CeraVe Hydrating Facial Cleanser. Comes in a nice pump. I really love how clean it makes my skin feel.
- Prescription tretinoin cream.
- CeraVe Moisturizing Cream. I chose the tub because it was cheaper per mL. Quite thick, good for dry Winters. They also have a lighter feeling ones, but this is good for my current dry climate and skin prone to dryness.
- After waking up:
- SPF 50 sunscreen. Re-apply around mid-day.
- If you are able to access them, Japanese and Korean sunscreens are amazing. Can't recommend them enough. They feel like you are not even wearing sunscreen. Leagues and miles ahead of Western sunscreens. This is apparently due to regulatory issues, and the fact that Westerners often ignore the instruction to re-apply sunscreen after a few hours of wear, which has incentivized Western sunscreen manufacturers to optimize for longer lasting (and slimier) sunscreens. Any time friend goes to Japan I tell them to bring me a huge supply of Bioré UV Aqua Rich SPF 50 sunscreen, which is really expensive in the West ($15-30), but really cheap in Japan (like, $4).
- I am not sure if you actually need to have sunscreen during days which have a relatively low UV index, but all the recommendations say you need to use sunscreen if you are using a retinol or tretinoin product, so maybe there is a reason for that. I tried researching the reason why your skin might be more susceptible to damaging itself, but didn't find anything that seemed obviously correct or applicable to topical use of retinol or tretinoin to me.
- SPF 50 sunscreen. Re-apply around mid-day.
I felt a bit validated when I saw that Bryan Johnson also uses CeraVe products, heh.
I change my sheets often, so I tend to skip using a cleanser in the morning due to laziness. If you don't change your bedsheets at least once a week, you might want to do cleanser in the morning as well.
While we're on the topic of skincare, skin can be very individual in how it reacts to things. I have always had crazily fussy skin and the thing that finally helped a lot after two decades of trying different things was snail mucin. Worth a shot if you've never heard of it and have issues. Some people are allergic to it so best to try a drop on your wrist or whatever.
Note that you have to use at least SPF50 sunscreen every day, including during winters, including when it’s cloudy (clouds actually don’t reduce UV that much) if you use tretinoin.
The linked sunscreen is SPF 45, which is not suitable if you’re using tretinoin.
(I used tretinoin for five years and it has had a pretty awful effect on my skin- it made it very shiny/oily. It’s unclear how reversible this is. At some point I learned that it’s a side effect of tretinoin and mostly stopped using it. Some people want their skin to look like that and go for tretinoin to achieve it; for me, it looks pretty unnatural/bad and I am very much not unhappy about it.)
The linked sunscreen is SPF 45, which is not suitable if you’re using tretinoin.
Unlikely to be advice that can be generalised.
- SPF is a measure of the reduction of UVB reaching your skin
- SPF 30 means 96.7% protection
- SPF 45 means 97.8% protection
- SPF 50 means 98% protection
- SPF 80 means 98.75% protection
- There isn't much difference between SPF 45 and SPF 50+.
- Tretinoin increases sensitivity to UV light, but the biggest factor is still the underlying sensitivity of individual skin. For some people SPF 30 may be more than enough, for others, SPF 50+ may not be enough for prolonged sun exposure.
Still important to make sure that you're using broad-spectrum (UVA + UVB) sunscreen, and that you apply it correctly.
(IDK anything about the underlying contingent facts, but:
- there's a large relative difference between .967 and .98; almost half as much distance to 1. If exposure is really bad, this difference could matter.
- If there's a damage repair mechanism with something like a rate of repair, that mechanism can either be overwhelmed or not overwhelmed by incoming damage--it's an almost discrete threshold. )
- For sure, but that leads to much more individualised advice of the form "If you're fine to be exposed to sun for up to 2h with SPF 50, you should not expose yourself for much more than 1h with SPF 30". The quoted section makes it seem like "You're fine as long as you wear SPF 50+ sunscreen, but SPF 45 just won't cut it.", which doesn't generalise for most individuals and their level of sunlight exposure.
It is true that cloud cover doesn't reduce UV as much as one might think, certainly. But there is a *huge* difference in UV levels between Winter and Summer in Northern Europe. Appopriate levels of sun-cream cannot plausibly be the same regardless of time of year. Time of day also makes a huge difference; if you're not going outside within 2-3 hours either side of the zenith (in theory noon; in practice moves up to 2 hours off this depending on exactly where you live, local time zones, and daylight saving), you can mostly forget about sun-cream.
There’s certainly a huge difference in the UV levels between winters and summers. Even during winters, if you go out while the UV index isn’t 0, you should wear sunscreen if you’re on tretinoin. (I’m deferring to a dermatologist and haven’t actually checked the sources though.)
Came across this site on x on my quest for skincare products/ingredients that can help with my extreme soft skin. I have a rare form of soft skin and it’s flappy was wondering if Tretinoid could help firm it up. Also why is it only applied on the face?
Not a critique of retinoids but your post is not extremely convincing, I've looked into anti-aging anti-wrinkle cosmetics and the world of products is filled with marketing speak. Reading your post it seems no different from frontpage Google blogs for retinoids or skincare or supplements. Seeing those before and after pics is surprising on a site that loves talking about RCTs and statistical power! But it's hard I'd like to challenge anyone to try googling "vitamin C wrinkles" and see if you can make a conclusion or understand which form or preparation is most effective if at all. Niacinamide, Ha, Ginseng, squalene, vitamins, caffeine... they can't all work can they?
Cosmetics/health stuff marketing is the name of the game here, just slap a bunch of cheap actives into a bottle and your brand and budget will carry you.
I was unable to come to firm conclusions or cut through blog spam / marketing speak, I personally chose to go for "peptides" (aka Matrixyl, matrikines).
- It has been studied to aid wound healing. And this study in Molecular Pharmaceutical, a journal on drug delivery instead of skincare/aging/cosmetic, seems proper https://pubs.acs.org/doi/abs/10.1021/mp300549d
- The first Matrixyl 3000 is patented/licensed by it's inventors (Sederma/Croda), which makes me believe it's 'moat' is its efficacy/trade secret compared with large cosmetics companies who's competive advantage are marketing/brand. The are a ingredients supplier to these companies, since they are B2B they aren't in the marketing game. There are also several similar newer competing 'peptides' that companies have spend R&D on
- For an active ingredient, it doesn't seem the trouble to make compared to many of the simpler ones if it didn't work. It's a triple amino acid that is later palmitoylated to increase topical absorption. That's is just a guess of course, but Palmitoylated-KTTKS doesn't roll off the tongue or look nice on a bottle
Even though they are licensed, they arent much more expensive than high end products with cheaper/ineffective actives. Anecdotally, my skin feels more supple. I have no idea which of the peptides works best
There's plenty of scientific evidence for the effectiveness of topical retinoids, going back several decades.
Thanks, this is interesting
I was wondering, do retinoids work as an acute treatment as well? I sometimes have annoying acne spots in various places, but I don't feel like preventatively slathering my whole body in the stuff
Hard to say. Retinols are recommended as a preventative. Though incidentally I have noticed acne fading much faster after using them. I suspect this is because they speed up the healing process of the skin.
No, retinoids work by normalizing skin function and usually take at least a few weeks of consistent use to show results. If you need an acute treatment, consider benzoyl peroxide or acids like AHA and BHA.
1Are you afraid of dry eyes/meibomian gland dysfunction at all? It seems like it's pretty common as a side effect of retinoids.
If you would like to buy Differin gel in a country where it is not over the counter such as the UK, you could buy it on iHerb. It is a US site which ships to other countries, I got some Differin gel from there shipped to the UK and it was less painful than figuring out how to get American Amazon or Walmart to ship abroad. But it is more expensive than the Amazon link OP provided, so I guess this is more of a thing if you want to try some out and see if it works for you with as few effort as possible (although beware that it doesn't work immediately, you will probably have to wait a couple months to start seeing results).
