IFRA 51, Diffusers & CLP – The No-Faff Version

IFRA (The International Fragrance Association) publish safety standards that tell you the maximum safe usage level of a fragrance oil in different types of products. These limits are grouped into categories, and reed diffusers sit in Category 10A under IFRA 51 Amendment.

If you are making reed diffusers, Category 10A is the only IFRA category you should be looking at.

Why Diffusers Are Category 10A

Originally, reed diffusers were classed as Category 11, which allowed much higher usage levels. Under IFRA 49 they were moved into Category 10A, which is stricter.

This change reflects how diffusers are actually used. They are open-top, continuously evaporating products, so the fragrance is constantly released into the air and have a small risk of skin contact from handling reeds. The exposure level is very different to a candle or a wash-off product, so IFRA tightened the limits.

Where We Are Now: IFRA 51 (Current Requirement)

We are now firmly on IFRA 51. IFRA 48, 49 and 50 are no longer acceptable to use for diffusers or any other home-fragrance product.

The deadline to move to IFRA 51 for both new and existing products was October 2025.

That means:

• All products on the market should now be using IFRA 51 certificates.
• There is no “carry on with the old IFRA until you sell through stock” option.
• The transition period is over – older IFRA versions are now out of date for compliance.
• Suppliers should have updated their documentation to IFRA 51.
• Makers are expected to update their own records and usage percentages to match.

If your supplier still only shows IFRA 48, 49 or 50, they are behind. You should be asking them for the IFRA 51 version of the certificate.

How to Find the Correct Usage Level for Your Diffuser

For reed diffusers, you only need to care about Category 10A. Here’s the simple process:

1. Go to your fragrance supplier’s website.
2. Open the IFRA 51 certificate for the oil you want to use.
3. Scroll to the line for Category 10A.
4. The percentage shown there is your maximum safe usage for reed diffusers.

Example: if Category 10A says 17%, you should not exceed 17% fragrance content in your diffuser base. That number is not a suggestion, it is the upper safety limit for that oil in that type of product.

What IFRA Does Not Do

This is where a lot of confusion starts, so let’s strip it right back. IFRA does not:

• Tell you which CLP hazards apply.
• Decide your pictograms or signal words.
• Generate or replace your CLP label.
• Sit inside GB CLP law in the same way as an SDS.

IFRA = safe usage guidance.
CLP = hazard classification law.

They are related, but they are not the same system, and one does not override the other.

How IFRA and CLP Work Together (The Simple Version)

The relationship between the two, for diffusers, looks like this:

IFRA tells you the maximum percentage you are allowed to use safely.
CLP tells you which hazards apply at the percentage you are actually using.

If you stay within the IFRA Category 10A limit, you are using the fragrance within the safety range that IFRA has set for that oil in reed diffusers.

Your CLP label then reflects whatever hazards occur at your chosen usage rate. You do not “get CLP from IFRA”, and you do not “fix CLP by changing IFRA”. They are separate pieces of the puzzle.

What If Your Supplier Hasn’t Uploaded IFRA 51 Yet?

By now, they should have. The October 2025 deadline has passed, so older versions are no longer current. If your supplier still only lists IFRA 48, 49 or 50:

• Contact them and request the IFRA 51 certificate for that oil.
• Do not recalculate or design new products based solely on outdated IFRA versions.
• Update your own documentation when the IFRA 51 sheet becomes available.

The No-Faff Summary

Diffusers = Category 10A
IFRA 51 is now mandatory for new and existing products  -the October 2025 deadline has passed.
Your diffuser load must not exceed the Cat 10A maximum on the IFRA 51 certificate.
IFRA gives you safe usage limits; CLP gives you hazard classification.
They work alongside each other, but they are not interchangeable and they do not replace each other.

Updated: January 2025 to reflect IFRA 51 and the October 2025 deadline.