Allergy to benzophenones
Benzophenones were declared the Contact Allergen of the Year for 2014 by the American Contact Dermatitis Society (ACDS).
What are benzophenones and where are they found?
The benzophenones are a group of aromatic ketones that have both pharmaceutical and industrial applications. They have both UVB and some UVA absorbing properties and act like optical filters to block out harmful UV rays, whether it be in a sunscreen agent to reduce skin damage or to retard photodegradation and extend shelf life in toiletries or plastic surface coatings.
|Pharmaceutical Uses||Industrial Uses|
The four main benzophenone derivatives that have been used widely in sunscreens and cosmetics are listed below. They share similar chemical and physical properties. Often benzophenones are used in combination with other chemical absorbing sunscreens to augment and stabilize the final product.
- Benzophenone 3 (2-hydroxy-4-methoxyphenyl: oxybenzone)
- Benzophenone 4 (2-hydroxy-4-methoxy benzophenone-5-sulfonic acid: sulisobenzone)
- Benzophenone 8 (2,2-dihydroxy-4-methoxybenzophenone: dioxybenzone)
- Benzophenone 10 (2-hydroxy-4-methoxy-4-methylbenzophenone: mexenone)
What are the reactions to benzophenone allergy?
The first contact reaction to benzophenones in sunscreen products was first documented in 1972. Benzophenone sensitivity produces classic allergic contact dermatitis as well as photocontact dermatitis. In benzophenone allergic individuals, products containing benzophenone or benzophenone derivatives may cause redness, swelling, itching and fluid-filled blisters. Symptoms may appear immediately or several days later (delayed contact and photocontact dermatitis). In severe cases anaphylaxis may occur.
In addition to allergic reactions, concerns have been raised about the relative ease of which benzophenones are absorbed into the skin and may promote generation of potentially harmful free radicals. Also, recent reports of oxybenzone having hormonal effects in animal studies has deterred some people from using sunscreen products. However these findings are not based on human studies and cannot be a reliable indicator of what happens in people. Benzophenones, including oxybenzone, combined with other sunscreen agents still provide excellent sun protection. The long-term use of these agents in sunscreens is unknown and further research is warranted.
Am I allergic to benzophenones?
Benzophenone allergy is diagnosed by performing special allergy tests, i.e. patch tests, with 5% benzophenone in petrolatum.
Treatment of benzophenone allergy
If you are diagnosed with benzophenone allergy then avoid exposure to benzophenone containing products. Management of benzophenone 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 benzophenone allergy?
Read product labels and avoid products that contain benzophenone or any of its derivatives. 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 benzophenone
- Diphenyl ketone
- Phenyl ketone
Formula: benzophenone – C13H10O
CAS number: 119-61-9
Cross reactions: none listed
Appearance: white flakes or crystals with rose like odour
Sensitizer: benzophenone and its derivatives
Patch test: 5% or 10% benzophenone in petrolatum