We love the sun — and we’re always seeking out adventures in warm, bright, beautiful places. But when it comes to sun protection for travelers, we’ve all been there: grabbing a last-minute bottle of sunscreen at the airport or a remote corner store because we forgot to pack it, didn’t bring enough, or never really looked into what makes a good one.

Then came the Galápagos — where reef-safe sunscreen is required — and that was our wake-up call. It sent us on a much-needed deep dive (pun intended) into what makes a sunscreen not just safe for the planet, but also truly protective for our skin.

Sun safety is absolutely part of wilderness medicine and staying prepared. That’s why we created this quick MedTreks guide to help you decode sunscreen labels, understand the difference between UVA and UVB rays, and build smart, sun-safe habits that let you enjoy every golden moment of your trip — safely and responsibly. 

 

UVA vs. UVB Rays: Why It Matters in Wilderness Medicine

Before diving into the label decoding, let’s take a quick moment to understand the two types of ultraviolet radiation that sunscreen is designed to block: UVA and UVB.

• UVB rays are the culprits behind sunburns and are strongest between 10 a.m. and 2 p.m. These rays directly damage the skin’s outer layers, leading to immediate burns and blistering, making them a key concern for outdoor adventurers.
• UVA rays penetrate deeper into the skin and are more closely linked to long-term skin damage, including premature aging, DNA damage, and skin cancers. They are present all day, year-round, and can even penetrate glass and cloud cover—making them a stealthier but no less serious threat.

For MedTreks travelers, especially those on high-altitude treks or long days on the water (where UV rays reflect off surfaces), understanding this difference is key. In wilderness medicine, we teach the importance of prevention over treatment—and that includes proactive sun protection to avoid burns, dehydration, infection risk, and skin damage as sun protection for travelers.

Understanding the Basics: The “Drug Facts” Label

The “Drug Facts” section on sunscreen labels provides essential information:

• Active Ingredient: Look for sunscreens with Zinc Oxide (ideally at 20%). Zinc oxide is a mineral-based UV filter that offers broad spectrum protection, physically blocking both UVA and UVB rays.
• Uses: These typically state that the sunscreen helps prevent sunburn and, when used correctly, reduces the risk of skin cancer and early aging caused by the sun.
• Warnings: Always check for:
  • “For external use only”
  • Avoid using on broken skin
  • Avoid eye contact
  • Stop use if rash occurs
  • Keep out of reach of children; seek help if ingested

 Proper Application is Key for Sun Protection for Travelers

Knowing how to apply sunscreen is just as important as picking the right one.

• Apply generously 15 minutes before sun exposure.
• Reapply often:
  • After 40 minutes of swimming or sweating
  • Immediately after towel drying
  • At least every 2 hours
• Sun Protection Measures:
  • Limit sun exposure during peak UV hours (10 a.m. to 2 p.m.)
  • Wear sun-protective clothing: long sleeves, wide-brimmed hats, sunglasses
• Kids Under 6 Months: Ask a doctor before applying sunscreen.
• Use Enough: Most adults need about one ounce (a shot glass full) per full-body application.

Decoding Key Terms on the Label

• SPF (Sun Protection Factor): Measures protection from UVB rays. SPF 30 blocks ~97% of UVB, SPF 50 blocks ~98%. Going higher gives marginal additional benefit—don’t rely on high SPF alone!
• Broad Spectrum: Indicates the sunscreen protects against both UVA and UVB rays. This is essential for full skin protection, especially in high UV environments like mountains and water.
• Water Resistant: Indicates sunscreen remains effective for 40 or 80 minutes of water exposure. No sunscreen is “waterproof,” so reapply frequently.
• EWG VERIFIED®: This label shows the product meets high safety standards, is free from harmful chemicals, and offers strong UVA/UVB protection.

Ingredients to Look For (and Avoid)

• Choose:
  • Zinc Oxide – mineral blocker, safe and effective
  • Titanium Dioxide (also mineral-based) is another good option
• Avoid:
  • Oxybenzone – linked to hormone disruption and coral reef damage
  • Retinyl Palmitate – may increase the risk of skin tumors in sunlight
  • Fragrance – can include hidden ingredients like phthalates, unless clearly marked EWG VERIFIED

Inactive Ingredients & Storage

Inactive ingredients often include moisturizers, thickeners, or scents. Examples may include Alcohol Denat., Glycerin, Tocopherol (Vitamin E), and Fragrance. Store your sunscreen away from excessive heat and direct sunlight to maintain effectiveness.

Final Thoughts: Sun Protection for Travelers

As medical professionals and outdoor adventurers, you’re constantly exposed to a variety of environments and sun conditions. From the equatorial sun in Costa Rica to reflective snowfields in the Alps, your sun protection strategy should be as well-informed as your wilderness medicine skills.

Choose broad-spectrum, zinc-based sunscreens, apply liberally, reapply frequently, and combine sunscreen use with other protective behaviors. You’ll reduce your risk of sunburn, stay comfortable on your trip, and set a great example for your patients back home. Curious what it’s like to practice wilderness medicine in the Galápagos? Read this beautiful reflection from one of our MedTreks faculty members who recently taught a course there.

Here’s to safe, healthy, sun-smart adventures — from all of us at MedTreks International!