9 Burning Sunscreen Questions Answered by a Dermatologist
Sunscreen is your single most important skincare step. It slows visible signs of aging, reduces dark spots and—most importantly—lowers your risk of skin cancer. But with so many options, confusing labels and myths, choosing the right sunscreen can feel overwhelming.
I’m Dr. Heather D. Rogers, a double-board certified dermatologist. In this guide, I answer your nine most asked sunscreen questions, explain how to choose the best formula for your skin and share what products I actually use on myself and my family. If you’re wanting more, check out my full blog with my top sunscreen recommendations.
1: What does SPF mean?
SPF stands for Sun Protection Factor. It measures protection against UVB rays—the ones that cause sunburn and DNA damage. SPF 30 blocks about 97% of UVB, while SPF 50 blocks about 98%. No sunscreen blocks 100%. Choose SPF 30 or higher and reapply every 2 hours.
2: Do I need a “broad spectrum” sunscreen?
Yes. Broad spectrum sunscreens protect against UVA rays (which cause wrinkles, discoloration and skin cancer) and UVB rays (which cause sunburn and DNA damage). Always choose a sunscreen with broad spectrum on the label.
3: What does PA++++ mean?
PA is a UVA rating system from Asia. More pluses (+) mean stronger UVA protection:
- PA+ = some protection
- PA++ = moderate protection
- PA+++ = high protection
- PA++++ = the best available
4: What’s the difference between mineral and chemical sunscreen?
- Mineral (zinc oxide, titanium dioxide): Sits on skin, reflects UV, safe for sensitive skin, pregnancy and kids. Downside: can leave a white cast.
- Chemical (avobenzone, octocrylene, etc.): Absorbs UV and reflects UV, usually lighter texture and blends easily. Downside: can be irritating and raises environmental concerns.
- Combination: Mix of both mineral and chemical.
5: How much sunscreen should I use?
- Face & neck: ¼ teaspoon (nickel-sized amount).
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Whole body: 1 ounce (a shot glass).
- Reapply every 2 hours, or after swimming/sweating/toweling off.
6: What does water-resistant mean?
The FDA only allows two claims:
- 40 minutes water resistant
- 80 minutes water resistant
After that, or after towel-drying, you must reapply. Using the claim “waterproof” is no longer allowed.
7: Are “reef-safe” and “natural” sunscreens regulated?
No. These are simply marketing terms. “Reef-safe” usually means the sunscreen is formulated without oxybenzone or octinoxate. “Natural” typically refers to mineral sunscreens. Always read the full ingredient list.
8: What is sunscreen “doping”?
Some sunscreens labeled “100% mineral” actually include unlisted chemical-like filters (such as butyloctyl salicylate). To avoid this, always check the drug facts box for FDA-approved active ingredients.
9: What’s the best sunscreen?
The one you will actually use every day. For sensitive skin or when pregnant, choose mineral zinc-based sunscreens. For oily or darker skin tones, a lightweight chemical sunscreen may blend better. And always remember, sunscreen is only part of sun protection. Add hats, sunglasses and shade for the best results.
Check out my full blog with product recommendations.
All product recommendations on this site are not sponsored and reflect the independent opinion of Dr. Heather D. Rogers, MD, based on her evidence-based research and extensive clinical experience as a practicing dermatologist. Links are provided for your convenience. Some may include discounts or commissions. Please shop wherever works best for you.
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