Yes, I’m also layering them…I’ve been swayed by the gazillion Instagram posts about azelaic acid and tretinoin. Not one or the other — together, stacked in the same routine, with captions like “the combo that actually fixed my skin” and a lot of before-and-afters.

Before adding anything new to my routine so went down the research rabbit hole that I’ve lovingly shared before for anyone else planing on introducing these ‘miracle’ ingredients to their routine. I’m still in the early days so can’t swear by it yet but hopefully I’ll have a before and after photo to share by Christmas with dewy, youthful looking skin.

What’s actually trending

This isn’t a fringe thing — azelaic acid has racked up around 300,000 TikTok mentions and roughly 200 million views on related posts over the past year. The posts that do best aren’t the product comparisons (those are everywhere and perform below average); it’s the “layering combo” posts, pairing azelaic acid with a retinoid, that pull in the highest engagement. One video walking through tretinoin for cell turnover and azelaic acid for inflammation and pigmentation got around 465,000 views and four times the usual engagement. Another, branded a “glass skin trio” of tretinoin, azelaic acid and SPF 50, hit 1.1 million.

So the trend is real, even if the phrase “glass skin trio” makes it sound more glamorous than two slightly medical-smelling creams and a sunscreen.

What each one actually does

Azelaic acid is antibacterial and anti-inflammatory. It’s commonly used for acne, rosacea (this is my issue and have been using this by itself for a couple of months now), redness and melasma or post-inflammatory dark spots — the marks acne leaves behind rather than the spots themselves. It’s gentle enough that it’s sold over the counter in the UK at concentrations up to around 10%, and it’s one of the few actives that’s generally considered safe in pregnancy (though check with your GP or midwife, not a TikTok caption).

Tretinoin is a prescription-strength retinoid — a different, stronger category to the retinol you’ll find on supermarket shelves. It speeds up cell turnover and supports collagen production, which is why it’s reached for on texture, fine lines, enlarged pores and stubborn sun-damage spots, as well as acne. It’s also considerably more likely to irritate skin than retinol is, and in the UK it’s prescription-only: you’ll need a GP, dermatologist or a registered online pharmacy consultation to get it, not a trip to Boots.

Why people are pairing them

There’s real research behind this, not just a trend cycle. Azelaic acid is reported to work better alongside a retinoid for acne and acne scarring, and the combination is specifically flagged as useful for hyperpigmentation — azelaic acid calming inflammation and fading pigment while tretinoin clears pores and resurfaces skin underneath it. On paper, it’s a sensible pairing rather than a random one.

How to actually do it without irritating your skin

The usual dermatologist-backed approach isn’t to pile both on at once:

• Introduce one at a time. If you’re new to either, start with just one for a few weeks before adding the second, so you know what’s causing any irritation.
• Split them by time of day. A common routine is azelaic acid in the morning and tretinoin at night, since retinoids break down in sunlight anyway. If you’re using both at night, apply the thinner formula first and wait for it to absorb.
• Start low and slow with tretinoin specifically. Begin with the lowest strength your prescriber gives you, and 2–3 nights a week rather than nightly, building up as your skin tolerates it.
• Moisturise properly. Both ingredients can be drying, so a proper moisturiser isn’t optional here — it’s part of the routine, not an afterthought. I also use a cica barrier cream since my skin is very sensitive.
• SPF is non-negotiable. Tretinoin makes skin more sun-sensitive. If you’re using it, daily SPF 30 or higher stops being optional.

And the one piece of advice that shows up everywhere: talk to a dermatologist or prescriber before combining them, especially once tretinoin is involved. They can advise on strength and how to build up, which matters more here than with most skincare because tretinoin is a genuinely active medication, not a serum.

If you want to start now

Tretinoin needs a prescription, so that’s not a today decision. But there’s nothing stopping you trying azelaic acid on its own first and seeing how your skin responds — The Inkey List’s Redness Relief Solution is a well-reviewed, affordable 10% azelaic acid serum aimed at sensitive and rosacea-prone skin, and a sensible place to start before you even think about adding a retinoid into the mix.

Watch out for

Redness, stinging, dryness and peeling are the most common complaints when people combine actives too quickly. Mild irritation when you first combine them is common enough, but if your skin becomes persistently sore, swollen or you develop a rash, stop and speak to whoever prescribed it rather than pushing through for the sake of the routine.

It’s a genuinely useful pairing if your skin can tolerate it — just treat it like the active medication it partly is, not a two-step trend to copy overnight.