Myth 1: Cloud coverage protects you from the sun
It’s an easy assumption to make. Less brightness, less heat, so less risk. But about 80% of UV radiation still gets through cloud cover, which is why sunburn on an overcast day catches people off guard. UVA rays, the kind linked to skin aging and deeper damage, pass through both clouds and window glass with little resistance. Cloud cover doesn’t buy you much.
Myth 2: You can’t get sunburned in water
Water doesn’t protect you either. UV can penetrate at least a meter deep, and the water’s surface reflects light back at you, adding to your total exposure. If you’re swimming or spending the day at the pool or beach, use a water-resistant sunscreen and reapply as soon as you get out.
Myth 3: SPF 100 means double the protection of SPF 50
This is where the numbers get misleading. SPF 30 blocks about 97% of UVB rays, the ones that cause sunburn. SPF 50 blocks about 98%. On paper, that’s barely a difference.
But look at what actually reaches your skin instead of what gets blocked. Picture two window screens facing a swarm of 1,000 mosquitoes. One stops 970. The other stops 980. Those numbers look close, but the first screen lets 30 mosquitoes through and the second lets 20. That’s a third fewer bites, even though both screens looked nearly identical on paper.
The same math applies here. Moving from SPF 30 to SPF 50 cuts the UV reaching your skin by more than a third. Moving from SPF 50 to SPF 100 gets you a smaller additional gain, since there’s less UV left to block.
There’s a bigger factor than the SPF number, though: how much you actually put on. SPF ratings are tested at a thickness most people never use in real life. Studies consistently find that people apply far less, which cuts into the protection they think they’re getting. A moderate SPF applied generously and reapplied every two hours protects you better than a high SPF applied thinly once and forgotten.
A few habits matter more than the number on the bottle:
- Use about an ounce, roughly a shot glass, to cover an adult’s exposed skin.
- Don’t skip the ears, back of the neck, hairline, lips, hands, and feet.
- Reapply every two hours, and right after swimming or heavy sweating.
- Lotions and sticks tend to give more even coverage than sprays.
- Add a hat and light clothing for extra protection on long days outside.
For more on how SPF actually works, see our breakdown of sunscreen labels.
Myth 4: If it’s in your blood, it’s unsafe
This is the question we hear most now, and it deserves a straight answer.
Yes, some sunscreen ingredients show up in blood after use. FDA-funded studies published in JAMA found that several active ingredients exceeded a threshold of 0.5 nanograms per millilitre, some after a single day of use. Oxybenzone showed by far the highest levels.²
Here’s the part that gets lost in most retellings: that 0.5 ng/mL threshold isn’t a safety limit. It’s the level the FDA set for triggering additional testing, not a level known to cause harm. Detecting something in the blood tells you it was absorbed. It doesn’t tell you it’s harmful. Those are two different questions, and mixing them up is where a lot of the fear comes from. The FDA has continued to recommend sunscreen use while this research is ongoing.
If absorption is still a concern for you, mineral sunscreens with zinc oxide or titanium dioxide sit mostly on the skin’s surface. In June 2026, the FDA also cleared a new active ingredient called bemotrizinol (BEMT), the first new sunscreen filter added in the US in about 25 years.³ It was designed to stay closer to the skin’s surface while covering a broad range of UV wavelengths. That’s not proof that it’s safer than everything else on the shelf, but it’s a newer option worth knowing about.
Myth 5: “Chemical” sunscreen is more dangerous than “Mineral”
Chemical and mineral are marketing terms, not safety categories. Mineral sunscreens use zinc oxide or titanium dioxide. Chemical sunscreens use ingredients like avobenzone, octocrylene, or homosalate. Both types absorb UV energy and release it as heat rather than simply sitting on top of your skin, which is a slightly different mechanism than most people assume.
What actually matters is the specific filter: how stable it is, how well it covers the UV spectrum, and how it performs in real-world use. That’s a more useful question to ask than “chemical or mineral.”
Myth 6: SPF tells you everything you need to know
SPF measures protection against UVB, the rays that cause sunburn. It says very little about UVA, which makes up most of the UV that reaches the ground, penetrates deeper into skin, and plays a larger role in aging and long-term damage. In the US, a “broad spectrum” label doesn’t guarantee UVA protection proportional to the SPF, the way it does in parts of Europe and Australia.
Visible light matters too, and conventional sunscreen filters don’t block it. If you deal with melasma or dark spots that seem to worsen despite sunscreen, a tinted formula with iron oxide covers that gap.
None of this means sunscreen doesn’t work. It means the number on the bottle answers one question, not every question.
Myth 7: You don’t need moisturizer in summer
Skin tends to run drier in winter, so it’s tempting to skip moisturizer once the weather warms up. But leaving skin to dry out can trigger more oil production to compensate, which raises the odds of breakouts. Keep moisturizing through summer. Just switch to a lighter formula if your skin feels greasy.
Myth 8: Sun exposure treats acne
This one is part myth, part fact. Sunlight can temporarily calm inflamed acne. But the trade-off isn’t worth it. UV exposure raises skin cancer risk over time, and it can darken existing acne marks, making them take longer to fade. A little daylight is fine. Chasing a tan to clear your skin isn’t a good trade.
