RUŌOD Lab

Level 10 · Safety, IFRA, Regulatory Compliance and Quality

Fragrance Allergens: Study Guide

Read our guide to fragrance allergens, then trace which ones your own formula would need to declare, working through invented compositions first.

Professional 20 min study By the RUŌOD Lab team Updated

In short

A fragrance allergen is a listed substance that some people react to, which many markets require on the label above a threshold. The EU's list grew by 56 under Regulation (EU) 2023/1545, with thresholds of 0.001% in leave-on and 0.01% in rinse-off products. New products have had to comply since July 31, 2026, and those already on the market have until July 31, 2028. The guide covers the list. This study guide has you do the tracing yourself, since most of the difficulty lies in naturals.

What you will learn

  • Say how a labelling threshold differs from a safety limit
  • Trace allergens contributed by natural materials
  • Know what EU leave-on and rinse-off thresholds apply to

Before this lesson: IFRA Certificates: Study Guide

Practice: invented compositions

A perfume is 15% concentrate. The concentrate holds 5% of an oil that a supplier document says holds 30% linalool, and 1% pure linalool. Both figures here are invented.

(0.05 × 0.30 + 0.01) × 0.15 = 0.00375, which is 0.375% in the finished product, well above 0.001%. Declared in the EU. Now work out how small the oil's share would have to be for it to fall below that threshold, and you will see why most natural-containing perfumes list allergens.

Practical exercise: Trace allergens through one formula

About 45 minutes · You will have: a table of allergen contributions and a provisional declaration list

  1. Take one of your formulas and state its market and product type.
  2. Find the current list for that market, and record its source and date.
  3. Ask your suppliers for allergen statements for each natural and each compound.
  4. Calculate each listed substance's share in the finished product, summing contributions.
  5. Write a provisional declaration list, in the required naming style. Mark any line with missing data.

You have done this well if contributions add up across lines, missing data is flagged, and the list is marked provisional until a qualified person has confirmed it. This exercise matters for the wearer, so don't guess a figure to complete a row.

Knowledge check

1. In the EU, a fragrance allergen is declared in a leave-on product above which threshold?
Show the answer

0.001%. Under Regulation (EC) 1223/2009 as amended by 2023/1545: 0.001% leave-on, 0.01% rinse-off.

2. Does a labeling threshold mean a material is safe below it?
Show the answer

No, it decides when a name appears on the label. Labeling lets affected people avoid a substance. Restrictions are a separate question.

3. Which formula line may contribute linalool?
Show the answer

Lavender oil, among others. Many naturals hold listed substances, so you need composition data from your supplier.

Sources

Further reading and materials

Written and reviewed by the RUŌOD Lab team. This is general education, not legal, regulatory, medical or safety advice. Example dilutions and exercises are for learning, are not validated products, and have not been safety-assessed. Completing a lesson confers no qualification. How we check these lessons.