Patch tests explained: when, how often and how to record them

This is general guidance, not legal advice. Follow your product manufacturer's instructions and check with your insurer and professional body for your own situation.

What a patch test is

A patch test applies a tiny amount of the product to a small area of skin, well before the full treatment, to see whether that person reacts. It is not a guarantee. It is a sensible early warning.

When it is advised

The NHBF code of conduct says clients for hair colour, eyebrow colour or eyelash tinting should be tested for possible allergies to PPD (a common dye ingredient) at least 48 hours in advance. NHS advice for home hair dyeing is also to test at least 48 hours before use and to follow the instructions on the packet. The NHS notes that symptoms of a hair dye reaction can take up to 72 hours to appear.

How long before, and how often

Timings differ. For tints and dyes, 48 hours is the figure in the sources above, but other products, such as lash adhesives or lifting solutions, vary by manufacturer. For anything else, including how often to repeat a test, the answer is: as your product manufacturer and insurer require. Look in the product instructions and your policy wording, and write the rule you follow into your own procedure.

Recording the result

Record at least:

• the client's name and the date and time of the test;
• the product, brand and batch if you can, and where on the body you applied it;
• the result when checked (clear, or what you saw), and the date;
• the client's signature or confirmation, and who carried out the test.

Link the record to the client's file so it is found at the treatment appointment.

If there is a reaction

Remove the product and tell the client not to proceed. Symptoms listed include stinging and burning, an itchy rash, dryness, tightness, soreness and blisters. A pharmacist can help with mild symptoms, and a GP should be seen if symptoms get worse. Call emergency services immediately if lips, mouth, throat or tongue swell suddenly, or if breathing becomes fast or difficult. Record the reaction, what you did and what you advised, and do not treat that client with that product.

Why a clear record matters

If a client later reacts, your record shows you tested, what you found and what you advised. Check with your insurer, because patch test records may be part of what they expect if a claim arises.

Do this next

1. Check each product's instructions for patch test timing and write them into one page of your own.
2. Check your insurance wording for any patch test condition.
3. Build a patch test record with the fields above.
4. Agree a standard script for booking the test with clients.
5. Write down your reaction procedure and keep it where you work.

The Finisher keeps patch tests on the client's record, and your reminder email asks for one when a treatment needs it and none is in date. See our page for your craft.

Sources

• NHBF Professional Code of Conduct for Salon Owners (2024) (read 22 Oct 2026)
• NHS, Hair dye allergy (read 22 Oct 2026)
• NHS, Hair dye reactions (read 22 Oct 2026)

Last checked 22 October 2026. General guidance, not legal or tax advice.

Read next

• Consultation and consent forms: what to ask, what to keep, how long

  A good consultation form protects your client and your business, and it only works if you ask the right things, keep it safe and keep it long enough.

  3 min read

• Why your clients' records should be yours, not your booking app's

  You are responsible for your clients' information, so it should live somewhere you control and can always get back out.

  4 min read

• Working from home or on the road: addresses, safety and travel time

  A few simple routines make visiting clients, or welcoming them to your home, safer and less stressful.

  4 min read