What is a cinnamate? Clinical presentation Diagnosis Treatment Prevention Alternative names Further information
A cinnamate is a compound chemically related to cinnamon oil and other cinnamon-related compounds that are used widely as flavourings and fragrances in many toiletries and cosmetics. Cinnamates are also potent UVB absorbers 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. 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. Its widespread use in sunscreen and cosmetic products has led to an increase in octocrylene sensitisation so that it is now a prime photoallergen of chemical-absorbing sunscreens.
Because cinnamate is chemically related to balsam of Peru, tolu balsam, coca leaves, cinnamic aldehyde, and cinnamic oil, people with sensitivities to these compounds may also be sensitive to cinnamate. 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 the generation of potentially harmful free radicals. What this means in terms of the use of cinnamates in skincare products long term is unknown, hence further research is warranted.
Cinnamate allergy is diagnosed by performing patch tests with 1% cinnamate in petrolatum.
If diagnosed with cinnamate allergy, 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.
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.
Formula: 2-ethoxyethyl p-methoxy cinnamate – C14H18O4
CAS number: 104-28-9
Cross-reactions:
Appearance: slightly yellow viscous liquid
Sensitiser: cinnamates and its derivatives
Patch test: 1% cinnamate in petrolatum
