Patch test a new product by applying a small amount to your inner forearm or behind your ear, then leaving it alone — no other new products over the top — for 24 to 48 hours before it goes anywhere near your face. If there's no redness, itching, stinging or bumps by then, it's very likely fine to introduce properly, starting slowly.
General information, not medical advice — always check with your GP, midwife or pharmacist about your own skin and any product you're unsure of.
Why postpartum skin needs this step more than most
If your skin has felt more reactive since having a baby — stinging at products that never used to bother you, going pink at the drop of a hat — you're not imagining it. Hormonal shifts and a temporarily weaker skin barrier are genuinely common after birth, and we've gone deep on why in Why Everything Suddenly Stings: Your Skin Barrier After Pregnancy. A barrier that's already working hard is more likely to react to something new, which makes patch testing far more useful right now than it was pre-baby.
It's a two-minute habit that saves you from finding out the hard way, on your actual face, at 11pm before a big day.
The proper patch test, step by step
Here's the version that actually tells you something, rather than a quick sniff-and-hope:
Pick your spot. Inner forearm or behind the ear both work well — skin that's reasonably sensitive but easy to keep an eye on.
Apply a small amount. About a 5-cent-piece size for a cream or serum, or a light layer if it's a toner or essence.
Leave it completely alone. No soap, no other new products over the top, for at least 24 hours — 48 is better if you have the patience.
Check at intervals. Look at 20 minutes (an immediate reaction), then again the next day (a delayed one). Both matter.
If it's clear both times, you're good to introduce it properly — but still slowly, see below.
What counts as a reaction (and what's normal settling-in)
A true reaction usually means redness, raised bumps, itching, stinging that doesn't settle, or swelling. That's a clear no for that product, at least for now.
A very brief tingle on application, especially with actives like vitamin C or niacinamide, that fades within a minute or two isn't unusual and isn't the same thing. If you're ever unsure which camp you're in, that's exactly what your GP or pharmacist is there for.
How to introduce a new product once it passes
Passing the patch test doesn't mean going all in. Introduce one new product at a time, every three to four days, so if something does turn up on your face, you know exactly what caused it. Start with a smaller amount than the packaging suggests, and give it a week before judging whether you like it.
This slow approach matters even more if you're breastfeeding and dealing with dryness on top of sensitivity — we cover that combination in Dry, Tight Skin While Breastfeeding: Why It Happens and What Helps. Rebuilding tolerance after birth takes a bit of patience; there's more detail on the process in Sensitive Skin After Pregnancy: How to Rebuild Your Skin's Tolerance.
Questions mums ask
How long should a patch test take before I trust it?
Give it a full 24 hours minimum, and 48 if the product contains actives like retinal, vitamin C or exfoliating acids — delayed reactions can take a day or two to show up.
Do I need to patch test gentle products too?
Yes, especially right now. Postpartum skin can react to formulas that never bothered you before, so even a "gentle" toner or moisturiser is worth the two-minute test.
Where's the best spot on my body to patch test?
Inner forearm or just behind the ear both work well. Avoid your neck or anywhere you'll accidentally wash it off within the hour.
Where to start
If you're rebuilding a routine from scratch for sensitive postpartum skin, The Barrier Repair Set ($188) is where I'd start patch testing — simple, calming formulas designed to work with a reactive barrier, not against it. Still pregnant or navigating that stage instead? The Pregnancy-Safe Routine ($185) is the one to test first.
Edwina x
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