Sunscreen ingredients explained

What do sunscreen ingredients actually do?

Ultraviolet radiation, or UV, includes UVA and UVB rays. UVA contributes to premature skin aging; UVB is the main cause of sunburn. Both contribute to skin cancer. Mineral and chemical filters mainly absorb UV and convert it into a small amount of heat. Mineral filters also reflect and scatter some UV, but reflection is not their main job. The familiar explanation that mineral sunscreen reflects while chemical sunscreen absorbs is too neat to be accurate.2

Which names should you recognize?

Sunscreens often combine filters to cover more of the UV spectrum and improve photostability, meaning the formula stays stable under light. A long filter list is not automatically redundant: avobenzone covers UVA, for example, while octinoxate covers UVB. Judge protection by the finished sunscreen's ratings rather than one familiar ingredient.3

Mineral, chemical or hybrid?

Mineral sunscreen is a useful option if chemical sunscreen irritates your skin. Chemical sunscreen is worth considering if a lighter, more transparent finish makes daily application easier. Neither category is automatically better for everyone. Less expensive sunscreens with the same ingredients can work as well as expensive ones, because the price tag is not a UV filter.45

What do SPF and broad spectrum tell you?

SPF means sun protection factor and mainly describes protection against UVB. Broad spectrum means protection against both UVA and UVB. SPF 30 protects against about 97% of UVB, while SPF 50 protects against about 98% when enough sunscreen is applied. Higher SPF does not extend the time between applications. A sunscreen's useful credentials are broad spectrum protection, SPF 30 or higher and water resistance, not a personality.13

What changed with bemotrizinol in the US?

On June 9, 2026, the FDA added bemotrizinol to the permitted active ingredients for US sunscreen. It was the first new active ingredient added to the US sunscreen monograph since the late 1990s. Bemotrizinol protects against UVA and UVB and has low absorption through the skin into the body. The FDA considers it generally recognized as safe and effective for adults and children aged 6 months or older. Bemotrizinol had already been marketed in Europe and other countries for years, so an ingredient's availability depends partly on where you shop.6

What about iron oxides, antioxidants and nanoparticles?

Iron oxides in tinted sunscreen add protection against visible light. Visible sunlight can worsen hyperpigmentation, meaning darkened patches of skin, particularly in darker skin tones. If dark spots are a concern, choose a tinted broad spectrum sunscreen with SPF 30 or higher. A tint that matches your skin tone can also make white residue less noticeable.12

Very small zinc oxide and titanium dioxide particles improve spreading and reduce white residue. No adverse effects from these sunscreen nanoparticles have been demonstrated; established sun protection benefits outweigh the theoretical risks. Added ingredients such as vitamin C and vitamin E have been studied for extra protection, but evidence for most ingredients that are not UV filters is weak.3

Which ingredients suit sensitive skin, pregnancy and children?

Mineral sunscreens are often a good choice for sensitive skin, rosacea or eczema, and for people who have reacted to chemical filters. Mineral sunscreen is also an option for oily or acne prone skin because it is less likely to clog pores. Texture still matters: a thick mineral formula feels different from a lightweight chemical formula. Creams suit dry skin, while gels suit oily skin and hairy areas.124

Many dermatologists prefer mineral sunscreen during pregnancy because zinc oxide and titanium dioxide have low skin absorption and a long history of use in pregnancy. Chemical sunscreen is not automatically off limits; both types can be appropriate. Daily protection is especially useful because pregnancy can increase susceptibility to melasma, a condition causing dark patches that sun exposure can worsen.2

Zinc oxide and titanium dioxide are useful choices for toddlers and children because they are less likely to irritate young skin. For babies younger than 6 months, prioritize shade and protective clothing, and talk to a pediatrician before using sunscreen.5

How do you get the protection on the label?

1. 1Apply sunscreen every day you go outdoors, including cloudy days and winter. Apply to dry skin before going outside: allow 15 to 30 minutes and follow the package directions.
2. 2Use a generous amount over exposed skin. Most adults need about 1 ounce for uncovered areas; body size changes the amount needed. Use at least 1 teaspoon for your face.
3. 3Cover your ears, neck, hands, tops of your feet and exposed scalp. Protect your lips with SPF 30 or higher lip balm.
4. 4Reapply about every two hours outdoors and after swimming or sweating, following the bottle's directions. Water resistant does not mean waterproof.

Lotions and creams usually give more reliable coverage than sprays. If using a spray, apply generously and rub it in evenly. Sunscreen works as protection during exposure, not as a treatment that needs weeks to show results. Combine sunscreen with shade, clothing, a hat and sunglasses.25

What if sunscreen causes a reaction?

Sunscreen can cause rash or skin and eye irritation. Discuss ingredient concerns or reactions with a healthcare provider or dermatologist. If sunscreen gets into your eyes, flush them with cool water for 15 minutes. Seek urgent help for breathing difficulty. If sunscreen is swallowed, seek medical advice immediately and do not induce vomiting unless instructed. In the US, Poison Help is available at 1 800 222 1222.47