Question: Is sunscreen still stable if it has avobenzone and octinoxate in it?
If your sunscreen only has avobenzone and octinoxate, then no, it is not stable. Avobenzone on its own is already very unstable and when combined with octinoxate, it is further destabilized. When both of these UV filters are degraded, your sunscreen will not provide adequate sun protection.
However, if your sunscreen has avobenzone and octocrylene, then the presence of octinoxate tends to have less of a destabilizing effect. Once octocrylene stabilizes avobenzone, avobenzone can coexist with octinoxate. However, the extent of any destabilization is unknown, especially since there may be other UV filters in the product. The percentage of octocrylene in the sunscreen formulation will also affect the photostability of avobenzone.
Therefore, I wouldn’t say a sunscreen with both avobenzone and octinoxate is useless, but it probably won’t be as effective as other sunscreens without this UV filter combination.
Here is a list of sunscreen filters that may stabilize avobenzone depending on the formulation:
- Enzacamene or 4-Methylbenzylidene camphor
- Parsol SLX
- Tinosorb S
- Tinosorb M
- Mexoryl SX
The following also help to stabilize avobenzone, though they are photostabilizers and not official UV filters:
- Butyloctyl Salicylate (HallBrite BHB)
- Diethylhexyl 2,6-Naphthalate (Corapan TQ)
- Diethylhexyl Syringylidene Malonate (Oxynex ST)
- Polycrylene (Polyester-8)
- Hexadecyl Benzoate
- Butyloctyl Benzoate
- Ethylhexyl Methoxycrylene (SolaStay S1)
Sunscreen manufacturers are also experimenting with microencapsulated avobenzone, which could potentially reduce how much it degrades and make it more stable.
Ultimately, the stability of a sunscreen containing avobenzone will depend on the formulation of the sunscreen and the presence of other UV filters and stabilizers.
Last updated: September 13, 2012
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