Reactions to hair dye can develop even after years of using the same product. A simple test before each use is the safest habit.
Quick look
- Many permanent and some semi-permanent hair dyes contain PPD, which can irritate skin or cause allergic reactions.
- Hair dye packs usually tell you to do a skin allergy test 48 hours before each use.
- Having had a black henna tattoo can raise your risk of reacting to PPD.
- The NHS says to call 999 if your lips, mouth, throat or tongue suddenly swell or you’re struggling to breathe.
Hair dye is safe for most people, but some develop an allergy to ingredients in it. Reactions range from an itchy scalp to severe swelling.
What causes reactions
According to the NHS, many permanent hair dyes, and some semi-permanent ones, contain a chemical called PPD (paraphenylenediamine), which is known to irritate skin or cause allergic reactions. You may be more at risk if you have, or have had, a black henna tattoo, because the paste used often contains a lot of PPD.
The skin allergy test
Hair dye instructions usually ask you to do a skin allergy test 48 hours before each use. Follow the instructions in the pack exactly, as they vary between products. A salon should also ask you to have a test before colouring your hair.
The NHS also suggests testing the dye on a strand of hair at least 48 hours before you use it, to check the colour and how your hair responds.
Little trick
Set a reminder on your phone two days before you plan to colour your hair, so the test never gets skipped.
Signs of a reaction
| Mild to moderate | Severe: call 999 |
|---|---|
| Stinging or burning | Lips, mouth, throat or tongue suddenly swelling |
| An itchy rash | Breathing very fast or struggling to breathe |
| Dryness, tightness or soreness | Throat feeling tight, or difficulty swallowing |
| Blisters | Skin, tongue or lips turning blue, grey or pale |
On brown and black skin, a rash may look darker brown, purple or grey, or be harder to see. Symptoms can take up to 72 hours to appear.
Safety check
If you have signs of a severe allergic reaction after using hair dye, call 999. If you’ve reacted to a hair dye before, don’t use it again, and speak to a pharmacist or GP before trying another product.
After a mild reaction
Rinse the dye off with plenty of water and stop using the product. A pharmacist can advise on treatments for mild itching or irritation, and you should see a GP if your symptoms get worse. If you colour your hair regularly, cutting back on heat styling helps keep it in good condition.
Ask away
I’ve used the same dye for years. Do I still need to test?
Yes. Allergies can develop at any time, even to a product you’ve used many times before, which is why instructions ask you to test before every use.
Is henna safer?
"Black henna" often contains high levels of PPD, so it isn’t a safer option. Check the ingredients of any dye and test before use.
How long can a reaction take to appear?
According to the NHS, symptoms can take up to 72 hours to appear.
This article is general information, not medical advice. For skin, scalp or allergy concerns, speak to a pharmacist, your GP or a dermatologist. In an emergency, call 999.