Allergy to cinnamates

What are cinnamates and where are they found?

Cinnamates are chemically related to cinnamon oil and other cinnamon-related compounds that are used widely as flavourings and fragrances in many toiletries and cosmetics. The added benefit of cinnamates is that it is a potent UVB absorber and therefore used in sunscreen agents and colour cosmetics with sun protection factor qualities.

Octyl methoxycinnamate is the most widely used UVB blocking agent used in the skincare industry. When exposed to sunlight, octyl methoxycinnamate is converted into a less UV absorbent form which means that its effectiveness is reduced over time. However, this breakdown can be partly prevented by the addition of certain other photostabilisers, particularly bemotrizinol. The combination with other chemicals makes a more water resistant and stable product.

Octocrylene (2-ethylhexyl-2-ciano-3, 3-diphenyl acrylate), a relatively new cinnamate that has both UVB and some UVA absorbing properties is photostable and thought to be non-allergenic and non-irritating. However, its widespread use in sunscreen and cosmetic products has led to an increase in octocrylene sensititsation, so much so that it is now a prime photoallergen of chemical absorbing sunscreens.

What are the reactions to cinnamate allergy?

Because cinnamates are chemically related to to balsam of Peru, tolu balsam, coca leaves, cinnamic aldehyde, and cinnamic oil, people with sensitivities to these compounds may also be sensitive to cinnamates. Sensitivity produces classic allergic contact dermatitis as well as photocontact dermatitis. Symptoms may appear immediately or several days later (delayed contact and photocontact dermatitis).

In addition to allergic type reactions, concerns have been raised about the relative ease of which octyl methoxycinnamate is absorbed into the skin and may promote generation of potentially harmful free radicals. What this means in terms of the use of cinnamates in skin care products long term is unknown, hence further research is warranted.

Am I allergic to cinnamates?

Cinnamate allergy is diagnosed by performing special allergy tests, i.e. patch tests with 1% cinnamate in petrolatum.

Treatment of cinnamate allergy

If you are diagnosed with cinnamate allergy then avoid exposure to cinnamate containing products. Management of cinnamate dermatitis may be treated as for any acute dermatitis/eczema; this may include treatment with topical corticosteroids and emollients.

What should I do to avoid cinnamate allergy?

Read product labels and avoid products that contain cinnamates or any of its derivatives. People with allergy to balsam of Peru and related cinnamon-type compounds should avoid sunscreens containing cinnamates.

Ask your pharmacist for advice and a suitable alternative. Your dermatologist may have further specific advice, particularly if you are highly sensitive.

Alternative names for cinnamates

• 2-ethoxyethyl p-methoxy cinnamate
• Cinoxate
• Isobutyl salicyl cinnamate
• Octyl methoxycinnamate
• Octinoxate
• Octocrylene (2-ethylhexyl-2-ciano-3, 3-diphenyl acrylate)

Further information

Formula: 2-ethoxyethyl p-methoxy cinnamate – C₁₄H₁₈O₄

CAS number: 104-28-9

Cross reactions:

• balsam of Peru
• tolu balsam
• coca leaves
• cinnamic aldehyde
• cinnamic oil
• esters of cinnamates

Appearance: slightly yellow viscous liquid

Sensitizer: cinnamates and its derivatives

Patch test: 1% cinnamate in petrolatum

Draft 24 July 2012