Several sunscreen ingredients raise legitimate health or environmental concerns, and a few common additives can trigger skin reactions in sensitive people. The short list of ingredients worth avoiding includes oxybenzone, octinoxate, fragrance, and certain preservatives. Beyond ingredients, the form of sunscreen matters too: aerosol sprays carry risks that lotions and creams don’t.
Oxybenzone: The Most Scrutinized Ingredient
Oxybenzone is the single most controversial active ingredient in sunscreen, and for good reason. When applied to the skin under normal conditions, it absorbs into the bloodstream at levels far exceeding what the FDA considers safe without further study. In clinical modeling, blood concentrations reached 196 to 253 nanograms per milliliter after just a few days of use, depending on sex. Those numbers are well above the 0.5 ng/mL threshold the FDA uses to determine whether an ingredient needs additional safety testing.
The concerns aren’t just theoretical. Oxybenzone has shown activity as a hormone disruptor in laboratory studies, and it’s been detected in breast milk, urine, and blood plasma in population-level surveys. Hawaii and Key West, Florida both banned the sale of sunscreens containing oxybenzone starting in 2021, citing damage to coral reefs. If you see it on a label (sometimes listed as benzophenone-3), it’s the single easiest ingredient to swap out, since plenty of effective alternatives exist.
Octinoxate, Homosalate, and Other Chemical Filters
Octinoxate (octyl methoxycinnamate) landed on the same ban list as oxybenzone in Hawaii and Key West because of its coral-bleaching effects. It also absorbs into the bloodstream and has shown estrogenic activity in lab settings.
Homosalate and octisalate are two other chemical filters that appear in many mainstream sunscreens. Recent research in zebrafish found that both chemicals disrupted thyroid hormones and growth hormone signaling. Exposed fish showed increased levels of thyroid hormones T3 and T4 while growth hormone and a key growth factor (IGF-1) decreased, ultimately reducing growth. Zebrafish aren’t humans, but these hormonal pathways are highly conserved across species, which is why the FDA has asked manufacturers for more safety data on these ingredients before classifying them as safe and effective.
Currently, only two active sunscreen ingredients carry the FDA’s “generally recognized as safe and effective” (GRASE) designation: zinc oxide and titanium dioxide, both mineral filters. A newer chemical filter called bemotrizinol is under review and may become the third. Every other chemical filter on the U.S. market sits in a gray zone where the FDA says it needs more data to make a determination.
Fragrance and Common Allergens
Sunscreen is a product you apply generously and repeatedly to large areas of skin, often on days when heat and sweat open your pores. That makes it a prime trigger for allergic contact dermatitis, and fragrance is the leading cause. In a study analyzing 52 high-SPF sunscreens sold in the U.S., fragrance was the most common high-risk allergen, present in 30 of the 52 products. U.S. labeling laws don’t require companies to list individual fragrance compounds, so “fragrance” on a label could mean dozens of undisclosed chemicals. If you have sensitive skin or any autoimmune skin condition, choosing a fragrance-free sunscreen is the simplest way to reduce your risk of a reaction.
Propylene glycol, a common solvent, appeared in 8 of 52 sunscreens in the same analysis. It’s generally well tolerated but can irritate people with eczema or those already sensitized to it.
Methylisothiazolinone and Preservative Risks
Methylisothiazolinone (MI) is a preservative that became widespread in personal care products during the 2000s and triggered an allergy epidemic. By 2017 and 2018, patch testing in North America found that 15% of tested patients reacted to MI, a remarkably high rate for a single allergen. In Europe, regulators urged companies to remove MI from leave-on products like sunscreen in 2013, and allergy rates subsequently dropped. The U.S. has been slower to act, and MI still shows up in some sunscreen formulations.
A related preservative, methylchloroisothiazolinone, carries similar risks. Both are classified as high-allergenicity ingredients. Other high-risk preservatives to watch for include formaldehyde-releasing compounds such as quaternium-15, diazolidinyl urea, and DMDM hydantoin. Check the inactive ingredients list, not just the active ingredients, since preservatives hide there.
Why Spray Sunscreens Deserve Extra Caution
Aerosol sunscreens create a fine mist that’s easy to inhale, and that changes the safety equation. Titanium dioxide nanoparticles, commonly used in mineral spray sunscreens, have been studied primarily as an inhalation hazard. CDC-reviewed research shows that inhaled nanoparticles can reach deep lung tissue and, at high doses, translocate to other organs. Long-term inhalation studies in rats have produced lung tumors, though the doses used were far higher than what you’d encounter from a quick spray at the beach.
A separate and more concrete risk involves benzene contamination. Benzene is a known carcinogen that isn’t an intentional sunscreen ingredient but has been found as a contaminant in aerosol products. Several major brands, including Banana Boat and Neutrogena spray sunscreens, have been recalled after testing detected benzene. Australia’s safety threshold is 2 parts per million, and some recalled products exceeded it. The contamination comes from raw materials in the propellant system, not from the sunscreen formula itself, which means it’s largely an aerosol-specific problem.
If you prefer sprays for convenience, apply them in well-ventilated areas, avoid spraying near your face, and never spray directly onto children’s skin. Spraying into your hands first and then rubbing it on eliminates the inhalation issue entirely.
Expired Sunscreen
An ingredient you should also avoid is the sunscreen already sitting in your beach bag from two summers ago. When sunscreen expires, its active ingredients break down and lose their ability to block UV radiation. You’re essentially applying a moisturizer with no sun protection. Mineral sunscreens develop a gritty texture with small pebble-like clumps that won’t rub in smoothly. Chemical sunscreens tend to turn yellow, become watery, and spread poorly. Any noticeable change in color, texture, or smell is a sign to replace the bottle. Most sunscreens carry a three-year shelf life from manufacture, but heat exposure (like a hot car) accelerates breakdown.
What to Use Instead
Zinc oxide and titanium dioxide remain the safest active ingredients by current evidence, carrying the FDA’s full GRASE designation. Modern mineral formulations have largely solved the old “white cast” problem through micronized particles and tinted bases. For people who prefer the feel of chemical sunscreens, filters widely used in Europe and Asia, like bemotrizinol, have strong safety profiles but are only now entering the U.S. market.
When shopping, flip the bottle and scan both the active and inactive ingredient panels. A sunscreen with zinc oxide as the filter, no fragrance, and no methylisothiazolinone in the preservative system covers the major bases. Lotion or cream formats avoid the inhalation concerns of sprays. The best sunscreen is one you’ll actually wear consistently, but with so many clean options now available, there’s little reason to settle for a formula built on the ingredients that raise the most red flags.