INGREDIENT · CHEMICAL FILTER
Avobenzone in sunscreen: absorption, stability and safety
Avobenzone is the filter many sunscreens rely on for UVA. It has two known quirks: it falls apart in sunlight unless something stabilises it, and it ends up in your blood after you use it.
You may see it written as
- Butyl Methoxydibenzoylmethane
- Avobenzone
What avobenzone is
Avobenzone is one of the most common UVA filters in sunscreens, and it is known to be photounstable, which means it degrades under sunlight.1 A filter that breaks down on the skin protects you less as the day goes on, so formulators add stabilisers.
On a label it usually appears as Butyl Methoxydibenzoylmethane, which is the same thing.
Why stability matters
A laboratory study tested whether antioxidants could keep avobenzone from degrading under simulated sunlight. Vitamin E, vitamin C and ubiquinone (coenzyme Q10) all helped. In a sunscreen formulation, ubiquinone was the most effective, and it also raised the SPF.1
Pairing matters too. A study of films of a commercial sunscreen containing avobenzone, oxybenzone and octinoxate found that avobenzone and octinoxate broke down together, faster than the expected E/Z isomerisation, and that irradiated film produced free radicals that persisted after the exposure had ended.2 That is a lab film, not skin, but it explains why a stable-looking formula is a matter of chemistry rather than luck.
How much of it gets into your blood
The FDA has said that sunscreen ingredients with systemic absorption above 0.5 ng/mL should have additional safety testing. A 2019 trial put four sunscreens on 24 healthy volunteers (a spray, another spray, a lotion and a cream), applied to 75% of the body four times a day for four days. Peak avobenzone levels in blood were roughly 1.8 to 4.3 ng/mL, all above the threshold.3
A larger 2020 trial of 48 people tested six ingredients. All of them, avobenzone included, passed 0.5 ng/mL, and they did so on day one after a single application. Avobenzone peaked at 7.1 ng/mL with a lotion.4
Both trials measured blood levels. They did not test for harm. What they show is that the FDA's request for more data was reasonable, and that the old assumption of 'it just sits on top' does not hold for chemical filters.
Avobenzone in pregnancy and breastfeeding
We found no pregnancy- or lactation-specific evidence for this ingredient.
Evidence on cosmetic products in pregnancy is limited overall, so ask your doctor or midwife about the specific product you use.5
What you will see on the label
On a label, look for Butyl Methoxydibenzoylmethane and Avobenzone. Snifff shows it as Moderate risk. For the rest of the formula, see what the score means and how to read the list.
As Snifff shows itButyl Methoxydibenzoylmethane
Pregnancy and nursing
We found no pregnancy- or lactation-specific evidence for this ingredient.
Wording as it appears in the extension, which can change between releases.
A FEW MORE ANSWERS
Common questions about avobenzone
Is avobenzone absorbed into the body?
Yes. In a 2019 trial, peak avobenzone levels in blood were about 1.8 to 4.3 ng/mL across four sunscreens, above the 0.5 ng/mL threshold the FDA uses to ask for more safety data.3
Is avobenzone stable in sunlight?
Not on its own. It is known to be photounstable,1 which is why formulas add stabilisers. In one lab study, ubiquinone was the most effective stabiliser tested.1
Does avobenzone mean the sunscreen is unsafe?
No. The trials measured how much avobenzone reaches the blood, not whether it harms you.3,4 Those results are a reason for more safety testing, not a verdict.
Is avobenzone safe in pregnancy?
Snifff found no pregnancy-specific evidence for Avobenzone. Ask your doctor or midwife about the product you use.
WHERE THIS COMES FROM
Sources
- Photodegradation of avobenzone: stabilization effect of antioxidantsAfonso S, et al. · Journal of Photochemistry and Photobiology B · 2014
- Unexpected photolysis of the sunscreen octinoxate in the presence of the sunscreen avobenzoneSayre RM, et al. · Photochemistry and Photobiology · 2005
- Effect of sunscreen application under maximal use conditions on plasma concentration of sunscreen active ingredients: a randomized clinical trialMatta MK, et al. · JAMA · 2019
- Effect of sunscreen application on plasma concentration of sunscreen active ingredients: a randomized clinical trialMatta MK, et al. · JAMA · 2020
- Cosmetic dermatology in pregnancy and lactation: a risk-benefit framework for clinical practiceKovacs T, et al. · International Journal of Dermatology · 2026
This page explains an ingredient. It is not medical advice, and it is not an assessment of any product. If you are pregnant, breastfeeding, or have a skin condition, ask your doctor or pharmacist.