Weather 
Fun in the sun can have a dark side.
Across the country, more than 88 million Americans get at least one sunburn every year — and while peeling skin might seem like a temporary annoyance, the damage can last a lifetime.
Research shows that suffering five or more sunburns doubles your risk of developing melanoma, the deadliest form of skin cancer. Even a single blistering sunburn in childhood or adolescence can significantly raise the odds.
Literally meaning “black tumor,” melanoma can show up as a new mole, a mole that’s changing or a spot with an uneven shape, border or color. It’s especially dangerous because it can quickly spread to other parts of the body if it’s not caught early.
And it’s becoming increasingly common. The Skin Cancer Foundation predicts 234,680 Americans will be diagnosed in 2026, a staggering 10.6% jump from last year.
It’s not all bad news, though. A mountain of research shows that wearing sunscreen every day can dramatically lower your risk of melanoma and other skin cancers.
But simply slathering some on isn’t always enough.
Dr. Shari Lipner, a dermatologist at Weill Cornell Medicine and NewYork-Presbyterian, says people regularly make common sunscreen mistakes that leave them vulnerable to painful burns and potentially deadly skin cancer.
Here are the eight biggest blunders she sees, plus three simple rules everyone should follow.
Mistake #1: Using too little sunscreen
Studies show most people apply just 20% to 60% of the amount of sunscreen needed for proper protection, leaving them more vulnerable not only to sunburn and skin cancer, but also premature aging.
“You should be using 1 ounce to cover all your skin,” Lipner told The Post.
That’s about how much can fit in a shot glass. You can also follow the “teaspoon rule”: one teaspoon for the face and neck, one for each arm, one for the chest and abdomen, one for the back and shoulders, and two for each leg.
Mistake #2: Not reapplying
“Not reapplying enough is one of the most common mistakes that I see in my practice,” Lipner said. “About 60% of the population does not reapply enough.”
In one study, every single one of the 22 people who didn’t reapply sunscreen got sunburned, while the eight who reapplied every one to two hours walked away unscathed.
“Sunscreen should be reapplied every two hours and immediately after swimming, sweating or towel drying,” Lipner said. “Even ‘water resistant’ sunscreen only last for 40 minutes.”
Mistake #3: Applying too late
Chemical sunscreens and broad spectrum sunscreens should be applied 15 minutes before going into the sun to allow for skin absorption, Lipner said.
Mineral sunscreens work differently. They sit on top of the skin and block UV rays immediately, so they start protecting you as soon as they’re applied.
Mistake #4: Missing easy-to-forget spots
Most people remember their arms and shoulders but forget smaller areas that are just as vulnerable, like the neck, nose, chin and skin around the eyes.
That’s bad news, because melanoma can appear almost anywhere — including the ears, lips and even eyelids.
Mistake #5: Rubbing it in too hard
“When you rub vigorously, the sunscreen can get lodged into the skin creases and some areas may be missed,” Lipner warned.
Research suggests that this can reduce the effectiveness by as much as 25%.
Instead, experts recommend gently spreading or patting sunscreen over your skin in an even layer and allowing it to dry.
Mistake #6: Depending on sprays and sticks
Sprays and sticks may be convenient, but they come with a catch. Unlike lotions, it’s difficult to tell whether you’ve applied enough — and they’re more likely to leave gaps.
“Sticks and spray applications tend to be uneven and miss areas,” Lipner said. “Lotions and creams give the most reliable coverage.”
Mistake #7: Having a false sense of security
“Some people spend too much time in the sun while they have sunscreen on and do not practice other important sun protective behaviors,” Lipner said. “Even when using sunscreen correctly, you should limit time in the sun, seek shade and wear sunglasses and sun-protective clothing.”
Mistake #8: Skipping sunscreen altogether
“The biggest mistake is not using sunscreen at all,” Lipner stressed. “Exposure to UV rays is the single most important modifiable risk factor for skin cancer. Therefore, not using sunscreen significantly increases your risk of skin cancer.”
It may sound obvious, but plenty of Americans still go without. One national survey found 11% never wear sunscreen, while only 13.5% say they use it every day as recommended. All skin colors can develop skin cancer.
And for good measure: 3 sunscreen rules to live by
Before heading outside, Lipner recommends keeping these three habits in mind:
- Choose a broad-spectrum SPF 30 at minimum. Since most people don’t apply enough sunscreen, a higher SPF can provide an extra cushion of protection.
- Be especially careful between 10 a.m. and 4 p.m., when UV rays are strongest — but remember they can damage your skin all day long.
- Check the UV Index before heading outside. Fewer than 7% of people do, according to one study, even though those who check are far more likely to put on sunscreen or seek shade.
