I am usually the first person to tell you to ignore a TikTok skincare trend - after all, influencers do not equal skincare clinicians or cosmetic chemists! However, there is one trend that is currently taking the app by storm - and best of all it originated (on the app) with a dermatologist.
The trend is called “skin cycling.” And here is everything you need to know.
What is Skin Cycling?
Skin cycling is a very simple concept - but it also kind of genius. It involves rotating your active skincare ingredients in the evening. You create a three or four day routine, and then just repeat it. Easy!
So what might it look like?
This will very much depend on what specific active ingredients you are currently using in your skincare routine. But it will go something like this:
Night One - Nurture your skin barrier. Stick to your routine of cleanser, gentle serum if you’re using it, and moisturise. Focus on hydration. Use humectants and ingredients for sensitive skin.
Night Two - Use your exfoliating product. This is often one of the alpha hydroxy acids (like glycolic acid), or a beta hydroxy acid (like salicylic acid for acne-prone skin). As a reminder, exfoliation is about the chemical removal of dead skin cells, allowing that dull top layer to slough off to reveal fresh new skin.
Night Three - Use your retinoid product. This is the gold standard of anti-ageing skincare with decades of clinical research to back it. It stimulates collagen, increases cell turnover, and improves the appearance of fine lines and wrinkles. However, retinoids can cause redness and irritation, in particular for those with sensitive skin, so this is where skin cycling can be idea.
Why Skin Cycle?
The benefit of this is that you are using your active skincare ingredients consistently, but you are using them in a way that is tolerated. This has been playfully coined the “cream cycle.”
I have often come across patients who will stick to a skincare routine for two weeks. Then drop it. Then pick it up for a few weeks. Then drop it again. When they come to see me in clinic, it becomes clear that they’ve used their skincare sporadically and inconsistently. Sometimes this is due to the side effect profile.
By cycling your active products, you are avoiding excess dryness, irritation, and dehydration.
See our summary in the slides below:
Let's start with a phrase you've said a hundred times without thinking about it: "mad as a hatter."
It isn't just a bit of whimsy from Alice in Wonderland. For centuries, hat-makers used mercury to turn animal fur into felt — and breathing its fumes, day after day, in poorly-ventilated workshops slowly poisoned them. The result was a syndrome doctors called erethism: tremors (the "hatter's shakes"), crippling anxiety and irritability, memory loss, personality change. An entire trade was, quite literally, being driven mad by a heavy metal. Mercury is a spectacular poison — it wrecks the kidneys and the nervous system — and we have known this for a very, very long time.
Which makes what I'm about to tell you all the more depressing. Because mercury didn't just disappear when the hat factories shut down. Today, it's in skin-lightening creams — and it's still poisoning people, right now, in 2026.