Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link

Summer Skin Myths Debunked

Commentary
05/20/16 Karen McKoy, MD, Senior Staff, Department of Dermatology, Lahey Clinic Medical Center


For most of us, the arrival of summer means spending a lot more time outdoors. But all those long days on the beach or lounging by the pool under a hot sun (or even on a cloudy day) increase your risk of doing permanent and painful damage to your skin. That’s a very serious risk—skin cancer is the most common cancer in the United States.

To make matters worse, much of what people assume about protecting themselves from sunburn and skin cancer isn’t based in hard science and in-depth medical research. In fact, a recent Harris Poll conducted on behalf of the Merck Manuals found that much confusion exits about skin protection.

As people get ready to hit the beach and start lathering up with sunscreen, let’s review the Poll findings and debunk five of the most common summer skin care myths.

1. SPF 30 sunscreen is twice as protective as SPF 15.

Poll Findings. 44% of Americans believe it.

Debunked. Sunscreen with a sun protection factor (SPF) of 15, when applied in scientific testing environments, blocks about 93 percent of the sun’s rays. SPF 30 blocks about 97 percent.

Once you get above SPF 30, the level of increased protection is insignificant. In fact, sunscreens with higher SPFs, and a lot more chemicals, can pose additional hazards, including allergic reactions and tissue damage. Lotions with additional chemicals can also be more environmentally damaging when they wash into the water supply.

2. A higher SPF will protect your skin longer

Poll Findings. 44% of Americans believe it.

Debunked. Higher SPF levels don’t protect you from the sun for longer periods of time, yet people are more likely to stay in the sun longer if they believe they’re better protected. In reality, sunscreen should be re-applied every 1.5 to 2 hours for prolonged protection. This misconception points to a larger issue with sunscreen use in general. Sunscreen should not be your main defense against the summer sun; it should be your last layer of protection.

Your two best defenses don’t even require chemicals:

  • Wear loose, ventilated clothing that covers most of your body
  • Stay out of the sun during the periods of high ultraviolet exposure in the late morning and early afternoon.

Here’s a good rule of thumb: If your shadow is shorter than you are, you’re at high risk of sunburn.

3. What you eat has no effect on how your body reacts to sun exposure.

Poll Findings. 32% of Americans believe what you eat has no effect on preventing sunburn.

Debunked. You may want to keep that lime out of your Corona the next time you’re enjoying a cold one in the sun. Contact with compounds in certain plants can lead to phytophotodermatitis, also known as lime disease or margarita rash. It’s an itchy, painful blister rash that worsens for about three days after skin that’s come in contact with the plant compounds is exposed to ultraviolet light. Lime juice is the most common cause, but celery, lemons, carrots, and parsley all contain the compound.

The condition is treatable with cold compresses and hydrocortisone cream, but it’s extremely painful. If you’re gardening or cutting up citrus fruit, it’s not a bad idea to wear gloves, and make sure to thoroughly wash your hands and arms before heading outside. It’s also worth checking your medications list for any that may also increase the chances of sun-induced reactions.

4. Spending time in the sun is important for getting enough Vitamin D.

Poll Findings. 62% of Americans believe it.

Debunked. Sunlight helps your skin produce vitamin D. Vitamin D is a good thing, but there’s an ongoing battle being waged by dermatologists and vitamin advocates over whether the benefits of soaking up vitamin D outweigh the risks of prolonged exposure to the sun. Yes, vitamin D is important to your health, but you shouldn’t risk sunburn or skin cancer to get it. Take a supplement and make sure you’re getting enough fortified foods—cereals and dairy products—that are rich in vitamin D.

5. Wearing a T-shirt in the water is an effective way to protect your skin from the sun.

Poll Findings. 30% of Americans believe it.

Debunked. A wet T-shirt does virtually nothing to protect against ultraviolet rays. In fact, a wet garment actually offers less protection than a dry shirt. If you want to wear clothing into the water, consider a more tightly-woven garment and make sure you’re also wearing sunscreen underneath it.

Baseball caps also offer less protection than many people think. Wearing a baseball cap can help protect your forehead and nose, but it does virtually nothing to protect your ears and neck. Hats that offer the most effective protection from the sun have 3-inch (7 centimeter) brims that cover or shade the entire head.

Survey Methodology

This survey was conducted online within the United States by Harris Poll on behalf of Merck Manuals from April 29 to May 3, 2016 among 2,015 adults ages 18 and older. This online survey is not based on a probability sample and therefore no estimate of theoretical sampling error can be calculated.


Dr. McKoy is the Manuals' editorial board member for Skin Disorders.