How to patch test skincare at home
Put a small amount on your inner arm, leave the area alone, and check it over the next 24 hours or longer. For a peel-off or wash-off product, use it as directed and watch the area afterwards. If your skin reacts easily, repeat it daily for 7 to 10 days. Redness, itching, swelling or a rash means don't use it on your face.
Why bother?
It's a small step that lets a problem show up on a patch of skin you can hide, rather than across your whole face. It's most worthwhile for anything with retinoids, acids, scented plant oils or a long ingredient list, and for anyone whose skin has reacted before.
The basic method
- Pick a spot. The inside of your arm is the usual place: easy to see, and out of the way.
- Wash and dry the area, and use a small amount.
- Use it the way you'd use it on your face. Peel or rinse off wash-off products after the time on the pack.
- Leave the area alone. No other products on that spot.
- Check it after an hour, at 24 hours, and at 48 hours if you can.
How long should you test?
- One go, 24 hours. It's quick and can catch strong irritation. It's the minimum we ask for.
- Repeated, 7 to 10 days. The American Academy of Dermatology's advice for sensitive skin is to apply the product to a small patch on the inside of your arm every day for 7 to 10 days, and use it on your face only if your skin stays clear. DermNet describes a similar test: twice a day on a 5 cm patch of forearm for 5 to 10 days.
Why so long? DermNet notes that allergic reactions usually occur unexpectedly, after something has previously been tolerated, so a single try might not show them. If your skin has a history of reacting, go with the longer option.
How to patch test a jelly mask
You don't need a full mix. Keep the same ratio of 3 parts powder to 2 parts water:
- Stir about a teaspoon and a half of powder into a teaspoon of cool water in a clean bowl.
- Smooth a little onto your inner arm in a thick layer.
- Let it set, and peel it off after 15 minutes.
- Rinse, and wait 24 hours before your first full mask.
Test each new formula, even if another has been fine, because each adds different ingredients. Each one's full ingredient list is on its formula page, so you can compare them first. Lavender and chamomile are examples some people react to.
Reading the result
| You see or feel | What to do |
|---|---|
| Nothing | A good sign, not a promise. Go gently on your face. |
| Slight pinkness that fades within an hour | Could be the peel or the rinse. Consider a longer test. |
| Itching, burning or lasting redness | Don't use it. Rinse, and use a plain moisturiser. |
| A rash, bumps or swelling | Don't use it. See your GP if it spreads or doesn't settle. |
| Swollen lips or face, or trouble breathing | An emergency: call 111. |
What a patch test can't tell you
- How your face will respond. A clear arm is a good sign, but your face can still react differently.
- Sun-related reactions. Your inner arm doesn't get the sun your face does.
- What exactly you're reacting to. That's the job of a medical patch test, usually done on the back over 48 hours. If you keep reacting to things, ask your GP.
DermNet also points out that highly irritant products may not be safe to test this way, so don't try this with something like a strong acid peel. Follow its own instructions instead.
Questions
Where is the best place to patch test skincare?
The inside of your arm. It's easy to watch, and it's out of sight if you do react.
How long should I wait after a patch test?
At least 24 hours, and longer if you can. If your skin reacts easily, repeating the test each day for 7 to 10 days gives you a better idea.
This is general information, not medical advice. If you're worried about your skin, see your GP or a skin specialist.
Sources
- 7 rosacea skin care tips, American Academy of Dermatology
- Patch tests, DermNet
- Contact dermatitis, DermNet