Tretinoin
If you wanna get the best possible anti-aging (and a bunch of other) effects from your skincare products, tretinoin (or one of the other form of retinoids) has to be in your skincare routine. Tretinoin works! It's proven and it's the gold standard in anti-aging technology . It's the real deal. Before we dive deep into this topic, let's just clear up some vocab : the word " retinoids " refers to a group of compounds that are all derived from vitamin A. Retinoids include beta-carotene (the thing in orange vegetables, like carrot or  sweet potato), retinol (pure vitamin A itself), and tretinoin. There are a few other forms, but let's not get caught up in the details too much. Retinoic acid is a kind of synonym for tretinoin, or to be exact all-trans-retinoic-acids are exactly the same as tretinoin. FYI, tretinoin is a naturally occurring thing and can be found in good quality rosehip oil . A little history Retinoids are not something new and the intense research into them started quite a while ago. In 1937 Paul Karrer won the Nobel prize for figuring out the structure of vitamin A. Twelve years later, retinol was successfully synthesized and since then, vitamin A derivatives started to pop up. Tretinoin itself was developed in the late 1960s by two guys named James Fulton and Albert Kligman. It was originally intended to treat acne but acne patients in the clinical trials started to report smoother and less wrinkled skin so the research into its anti-aging benefits soon began. It went so well, that the data was submitted to the FDA (the authority that approves drugs in the US) and it approved tretinoin for "use against photo damage" . Even today, tretinoin is the only thing approved by the FDA in the topical anti-aging field, so it's a really big deal. All-around magic for skin health Dr. Leslie Baumann writes in her great Cosmetic Dermatology book that "there are more than 125 distinct dermatologic disorders for which there is credible evidence of retinoid efficacy ". Don't worry, we will not list out all of them, but if you have one (or more) of the common skin problems (like wrinkles, loss of firmness, dull skin, acne or hyperpigmentation), retinoids will improve this. The reason why retinoids, especially tretinoin, are such an all-around skin problem solver is that they work on the skin at a cellular level and they make your skin cells behave in a healthy and normal way . Our skin cells contain retinoic acid receptors and tretinoin binds directly to these receptors and changes basic cell behaviour, like gene expression . Anti-aging effects in more details When it comes to skin aging, collagen plays a big role. It acts like tent poles that make sure the tent fabric is nice and firm. Adding collagen to the skin from your serums/moisturizers does not work, though. It's like throwing poles at a ramshackle tent on the ground and hoping that the poles will magically fall into the right place and erect the tent, it simply does not work that way. You can do two other things: one is to preserve the existing collagen in your skin as much as possible and the other is to convince the skin to create some more. The former will prevent wrinkles and loss of firmness, the latter has a chance to repair some of the existing damage. Tretinoin is great because it works in both ways. It inhibits collagen-destroying  enzymes called matrix metalloproteinases (MMPs, that are increased by UVB) and it's also proven to boost the skins own collagen synthesis . If that wasn't enough, tretinoin also helps aging skin in a bunch of other ways: it stimulates not only collagen (type I and III), but other important skin elements as well, e.g. natural moisturizing factor glycosaminoglycans (GAGs), or the skin protein, filaggrin. It also makes the epidermis thicker and compacts the outermost layer of the skin, the stratum corneum . The net result of all the things tretinoin does is less wrinkled, firmer, smoother and tighter skin. Simply put, pretty much everything you could want from an anti-aging ingredient. Other things tretinoin can help with We have already written that tretinoin was originally developed to treat acne, and it does. It normalizes keratinization meaning that it prevents dead skin cells from sticking together and clogging the pores. Not only that, but it also makes your pores produce less sebum that helps the pores to stay nice and clean and not get clogged up by an excess sebum and dead skin cells. Another notable benefit of tretinoin is skin lightening . It works by both preventing clumping of melanin in basal cells (skin cells at the bottom of the epidermis) and by accelerating epidermal turnover and so the loss of melanin. However, the skin lightening effect is not as strong as the gold-standard hydroquinone . In Tri-Luma cream , a prescription treatment for melasma, tretinoin, hydroquinone and a mild steroid are all combined to achieve clinical results. What's the catch (aka side effects) We often wonder why medicines, just like life, work in such a tricky way that the bigger positive effects almost always come with bigger negative side effects. This is definitely true for tretinoin and younger looking skin does not come without side effects. The most common ones are irritation, skin flaking and redness . As tretinoin (and retinoids in general) boosts the proliferation of skin cells, the "excess" stars to visibly flake. This usually happens about 2-4 days after starting a tret treatment and it's kind of normal. If you want fewer side effects it's good to know that more is not always better with tretinoin. A study in 1995 compared 0.1% and 0.025% tretinoin creams and found that the improvement of photoaging was similar but the irritation was much bigger with the 0.1% version. Another common side effect is dry (or drier) skin . It seems that tretinoin increases the amount of water that evaporates from the upper layer of the skin (this is called Trans Epidermal Water Loss) and might also decrease ceramide synthesis at least in the short term. Using a good moisturizer next to a tret treatment is a wise move. You also have to know that you should not use tretinoin (and retinoids in general) when you are pregnant . If you are taking Accutane (or the EU version Roaccutane) make 100% sure not to get pregnant whilst on these treatments. If you do not take it in the form of medicine but just slather it on your face, the teratogenic effect is less established. What's more, there is a study from 1993 concluding that "topical tretinoin is not associated with an increased risk for major congenital disorders". But when it comes to pregnancy, we say it’s best to be overcautious and do not use any retinoids in any shape or form. How to use If you are still with us (thank you! :)) and the possible side effects have not scared you off, here are a couple of tips about starting a tretinoin treatment so that you can minimize the side effects and maximize your (skins) happiness: Always use retinoid products in the evening (Not because they are photosensitizing but because retinoids tend to have poor stability when exposed to UV light.) Do not use too much, a pea size amount of product is more than enough. In the beginning, you can dilute it with an equal amount of moisturizer. If your skin is on the sensitive side, wait 15 mins after washing your face or after putting anything else on the skin so that your skin is totally dry which also helps to reduce irritation. Introduce tretinoin treatment in your life gradually, start every third night for the first 2 weeks. If everything is good (we mean no visible irritation) increase to every other night for another 2 weeks. If everything is still good, you can try every night. Be extra gentle with your skin in every other way : be careful with acids (wait 30 minutes between treatments, or use in the morning or on separate nights), do not use harsh scrubs or microdermabrasion (we think it's a wise move anyway), and do not wax your face. Bottom line : If your main skin concern is anti-aging and you like to use the tried and true solution , your best bet is a tretinoin (or another retinoid) treatment. Be careful with it though, watch for side effects, find the right strength for your skin's level of tolerance and your skin will thank you.