What is oxybenzone?

Oxybenzone is a popular ingredient in sunscreens. It’s a synthetic chemical from a group called ‘benzophenones’, many of which are also sunscreen ingredients.

As an organic molecule, oxybenzone is classed as a chemical sunscreen, as opposed to mineral sunscreens like titanium dioxide.

How does it work? 

Sunscreens protect your skin from damage by UV rays from the sun. As well as causing sunburn, some wavelengths of UV can directly damage your cells’ DNA, causing mutations which can develop into cancer. Other wavelengths of UV generate reactive molecules called free radicals inside your cells. These also attack and damage your DNA. Your body tries to prevent damaged cells from becoming cancer cells by triggering inflammation in the sunburnt area. Unfortunately this inflammation damages the collagen in the area, leading to wrinkled and prematurely aged looking skin.

Like many chemical sunscreens, oxybenzone has ring shaped molecules which are good at absorbing UV light. Once absorbed the light loses some energy and is shot back out again but not as UV and instead may be visible or infrared light. By soaking up and changing the UV light that hits your skin, oxybenzone prevents UV light from entering your skin cells and damaging them. Different molecules absorb different wavelengths better so a mix of several are usually used to increase coverage and protection.

Safety 

Side effects: 

Oxybenzone allergy is relatively common and often causes photocontact dermatitis; a condition where the skin doesn’t get inflamed until sunlight hits the area oxybenzone was applied to.

Some of the oxybenzone that gets applied to your skin get absorbed all the way into your body where it circulates until it is expelled in the urine. There is some controversy where it is thought that oxybenzone can mimic and interfere with human sex hormones like oestrogen and testosterone. Tests on cell cultures and lab animals have shown this effect but no live human study has confirmed these suspicions [1].

Benzophenones are also thought to contribute to coral bleaching as the sunscreen on swimmers washes off into the ocean and kills coral populations.

Interactions with other medicines: 

There are no known oxybenzone drug interactions.

Other names: 

(2-Hydroxy-4-methoxyphenyl)phenylmethanone, 2-Benzoyl-5-methoxyphenol, 2-Hydroxy-4-methoxybenzophenone, 4-Methoxy-2-hydroxybenzophenone, 4-Methoxy-2-hydroxybenzophenone butyric acid, Benzophenone-3