Allergy to avobenzone

What is avobenzone and where is it found?

Avobenzone is a dibenzoylmethane derivative and is a chemical substance that is used in sunscreen products. It is able to absorb the full spectrum of UVA rays and has been around since the 1980’s in sunscreen formulations worldwide. It does not provide protection against UVB rays.

More recently, studies have shown that avobenzone is photo-unstable and degrades quickly when exposed to sunlight. It can lose up to 50-90% of efficacy in the first hour of sun exposure. For this reason, avobenzone is now often formulated with photostabilising chemicals such as octocrylene and bemotrizinole. Other studies have shown absorption of avobenzone by the skin and have cautioned its use as with PABA-containing sunscreen agents.

What are the reactions to avobenzone allergy?

Avobenzone appears to be fairly well-tolerated although it has been associated with causing photocontact dermatitis in some individuals. It may also produce classic allergic contact dermatitis.

Another dibenzoylmethane derivative, isopropyl dibenzoylmethane (Eusolex 8020), was found to cause a high number of photosensitivity reactions and for these reasons was discontinued in 1993.

Am I allergic to avobenzone?

Contact allergy to pure avobenzone is rare. Most allergic reactions arise from the other chemicals avobenzone has been formulated with to make it more photostable.

Avobenzone allergy is diagnosed by performing specific patch tests and photopatch tests.

Treatment of avobenzone allergy

If you are diagnosed with avobenzone allergy then avoid exposure to avobenzone containing products. Management of avobenzone 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 avobenzone allergy?

Read product labels and avoid products that contain avobenzone or dibenzoylmethane derivatives. Your dermatologist may have further specific advice, particularly if you are highly sensitive.

Alternative names for avobenzone

• Butyl methoxydibenzoylmethane
• Parsol 1789

Further information

Formula: C₂₀H₂₂O₃

CAS number: 70356-09-1

Cross reactions:

• isopropyl dibenzoylmethane (Eusolex 8020)

Appearance: colourless crystals

Sensitizer: dibenzoylmethane derivatives

Patch test: avobenzone 10% in petrolatum