The substance Cinnamaldehyde; 3-phenylprop-2-enal; cinnamic aldehyde; cinnamal [1] / (2E)-3-phenylprop-2-enal [2] (CAS No.104-55-2 [1] / 14371-10-9 [2], EC No.203-213-9 [1] / - [2], INCI: Cinnamal) is an ingredient listed in the Cosing, with the functions: Denaturant, Perfuming, Flavouring.
It is one of the “historic” allegens and is listed in Annex III/76 of European Cosmetics Regulation 1223/2009, which states that the presence of the substance must be indicated in the list of ingredients when its concentration exceeds 0.001% in leave-on products and 0.01% in rinse-off products.
The 21st ATP of the European CLP Regulation 1272/2008 (applicable from September 1, 2025) has added it to its Annex VI/606-155-00-6, with the classification: Skin Sens. 1A, H317 - May cause an allergic skin reaction.

The Netherlands proposes to classify the substance as follows.

Identification
Index number
• 606-155-00-6
Chemical name
• Cinnamaldehyde; 3-phenylprop-2-enal; cinnamic aldehyde; cinnamal [1] /(2E)-3-phenylprop-2-énal [2]
EC numbers
• 203-213-9 [1] / - [2]
CAS numbers
• 104-55-2 [1] / 14371-10-9 [2]
Classification
Hazard class and Category code(s)
• Skin Irrit. 2
• Eye Irrit. 2
• Skin Sens. 1A
• Aquatic Acute 1
• Aquatic Chronic 2
Hazard statement code(s)
• …