7 sunscreen myths debunked

Myth #1: SPF30 blocks twice as many UVB rays as SPF15

In our 2023 Sun Smart Survey, we found there’s confusion about what the SPF numbers on sunscreens mean. Only 23% of people disagreed (correctly) that SPF30 blocks twice as many UVB rays as SPF 15, while an additional 21% didn’t know.

Remember, no sunscreen blocks 100% of UV rays.

• SPF50 blocks 98%.
• SPF30 blocks 97%.
• SPF15 blocks 93% of UVB.

Myth #2: SPF50 does not need to be applied as often as SPF30

Just 38% of people in our Sunsmart Survey disagreed with the statement that SPF50 doesn’t need to be reapplied as often as SPF30 (they were right!) – 26% wrongly agreed with this statement and 14% didn’t know.

All sunscreens, regardless of SPF, should be reapplied every 2 hours while you’re outside. Sunscreens also need to be reapplied after swimming, mopping up sweat or towelling dry.

Myth #3: ‘Reef-safe’ or ‘reef-friendly’ sunscreens are better for the environment

When we updated our sunscreens database, we found a number of brands claiming that buying their sunscreen will help protect the planet as well as your skin.

The most common claim we found was that sunscreens were “reef-safe” or “reef-friendly”. But there’s no regulations around what these claims mean, little consistency in which products use it, and the science about the threat sunscreen poses to the environment is still evolving.

Sunscreen expert John Staton told us water-resistant sunscreens that comply with the mandatory Australian and New Zealand sunscreen standard are inherently more coral reef and aquatic environment friendly, compared with sunscreens made to comply with other sunscreen standards from different countries. Staton said that, in theory, a 2-hour or 4-hour water-resistant product should almost not wash off at all.

Using sunscreen is a balancing act between protecting your skin and minimising potential harm to the environment. Check out our sunscreen tips to protect your skin and the ocean.

Myth #4: Having a tan means you don’t need as much sunscreen

A tan is a sign that skin damage has already started, so you should be more careful about protecting it. Any further UV radiation will only add to the damage, resulting in wrinkled leathery skin and possibly skin cancer later in life.

Myth #5: Children need a special sunscreen

Sunscreens specially formulated for children have a mild base for sensitive skin. But there’s no reason why kids shouldn’t use the family sunscreen if it doesn’t irritate their skin. Test a small amount on the inside of a child’s forearm for a few days to check if their skin reacts.

Infants have a thin, less-developed skin barrier and are more likely to be irritated by ingredients. The New Zealand Dermatological Society Inc (NZDSI) recommends infants use mineral sunscreens. Such sunscreens don’t irritate and provide excellent broad-spectrum protection.

Mineral sunscreens aren’t always labelled as children’s sunscreens, but you can be comfortable using whatever brand you prefer, whether it’s labelled for babies or children or not.

Keep babies and toddlers out of the sun as much as possible. The best protection for them is staying in the shade and using sun-protection clothing – as it is for everybody.

Myth #6: Using sunscreen can lead to a vitamin D deficiency

Vitamin D helps us build and maintain healthy bones and teeth and improves our immunity. It’s difficult to get enough vitamin D solely from food and our bodies produce it when we get sun on our skin.

How much sun exposure you need depends on different factors, such as your skin colour, where you live, how much skin is exposed, the season and time of day, and how much vitamin D you get from food.

The NZDSI says that usual recreational use of sunscreens doesn’t lead to vitamin D inadequacy. Sunscreen is a filter, not a block. This means sunscreen-protected skin still produces some vitamin D, but the process takes longer.

If you have fair skin, it takes less than 3 minutes of midday summer sun to make enough vitamin D if you’re wearing shorts and a T-shirt (for people with darker skin it takes longer). Being physically active outdoors helps you make more vitamin D than resting in the sun.

The NZDSI recommends if you’ll be outside for more than 3 minutes, to apply sunscreen to all exposed skin. It’s important you don’t get sunburnt while getting your vitamin D hit.

If you think you’re not getting enough vitamin D, talk to your doctor. Some people with a vitamin D deficiency may need to take a supplement.

Myth #7: You don’t need sunscreen on a cloudy day

According to the World Health Organization, UV rays can be high even on a cloudy day, so you still need to wear sunscreen.

Understanding the UV index (UVI) is helpful to alert you about when the sun’s rays are the most damaging. The UVI measures the level of radiation from the sun. It takes into account several factors, including the time of day, cloud cover, altitude and closeness to the equator.

The higher the UVI number, the greater the risk, and the less time it takes to cause skin and eye damage. In summer, New Zealand’s UVI can get up to 12 (but can exceed 13 in the far north). When the UVI is 3 or higher, sun protection is recommended.

It’s also important to consider how long you’re outside. Spending long periods outside, even when the UVI is low and you don’t get sunburnt, can add up and cause skin damage.

You can check UV data for your location with the free UVNZ or UV2day apps, or the Cancer Society’s Sun Protection Alert.

Compare 150+ sunscreens in our sunscreen database and find out more about sunscreens including our frequently asked questions.