Sun Exposure: Fact and Fiction?

Are the social media rumours about sunscreen and sun damage true?

Sun protection has become a surprisingly contested topic. Social media has circulated a range of claims about sun exposure, sunscreen and skin cancer — a mixture of old misconceptions and newer misunderstandings. It is worth clearing these up, because acting on inaccurate information has real consequences. Skipping sunscreen in the mistaken belief that it is harmful is a poor trade in a country with one of the highest skin cancer rates in the world.

Can research be misunderstood?

One recurring online claim is that a study showed a link between sunscreen use and a higher incidence of skin cancer. Some studies have indeed observed an association — but an association is not a cause, and two things explain it.

The first is confounding. People who spend the most time in the sun are also the people most likely to buy and apply sunscreen. Their higher skin cancer rate reflects their sun exposure, not the product they used to reduce it.

The second is behavioural, and is sometimes called the "sunscreen paradox". Some people treat sunscreen as a licence to stay outdoors longer, or feel they are effectively immune to burning once it is on. The result is a higher total UV dose despite the protection.

Does sunscreen cause skin cancer?

There is no good evidence that regulated sunscreen causes skin cancer. In Australia, sunscreens sold primarily for UV protection are regulated by the Therapeutic Goods Administration (TGA) as therapeutic goods, and their ingredients are assessed for safety and efficacy.

What we do know is that UV radiation damages skin cells and increases skin cancer risk, and that regular sunscreen use reduces it. The Nambour Skin Cancer Prevention Trial in Queensland — a randomised controlled trial — found that participants assigned to daily sunscreen use had a significantly lower rate of invasive melanoma than those using it at their own discretion, along with a reduced rate of squamous cell carcinoma.

A lower risk, however, is not the same as no risk. Sunscreen should not be treated as permission to spend unlimited time at the beach or in the middle of the day. It is also a mistake to apply it once in the morning and stay outside all day. Sunscreen needs to be reapplied every two hours, and immediately after swimming, sweating or towel drying. It works best alongside protective clothing, a broad-brimmed hat, shade and sunglasses.

Is applying sunscreen properly the bigger problem?

For most people, the issue is not whether sunscreen works but whether it is being used correctly. Research consistently shows Australians apply too little, apply it unevenly, and forget to reapply.

The guidance is straightforward:

• Apply 20 minutes before going outdoors.
• Use roughly one teaspoon (5 mL) per body area — face and neck, each arm, each leg, front of the body, back of the body. That is about seven teaspoons, or 35 mL, for a full adult application.
• Reapply every two hours regardless of what the label claims about water resistance, and immediately after swimming, sweating or towel drying.
• Choose a cream or lotion rather than an aerosol, which is difficult to apply at an adequate thickness.

Early morning and late afternoon sun can still cause problems

Another common misconception is that only strong midday sunlight causes skin damage. In truth, the risk depends on the UV Index, not on how hot or bright the day feels. UV levels are generally lower early in the morning and late in the afternoon, but low is not zero. The UV Index can still reach 3 or above outside the middle of the day, which is enough to cause damage.

Repeated exposure during ordinary activities — walking, gardening, or simply sitting outdoors — gradually adds to cumulative UV damage. This matters because skin damage does not always announce itself as sunburn. UV radiation can damage DNA in skin cells without the skin becoming red or painful. Over many years, that accumulated damage contributes to premature skin ageing and skin cancer.

Common sun myths on social media

Surveys suggest a meaningful number of people have reduced or stopped using sunscreen based on what they have seen online, and that younger audiences in particular rely on social media influencers for skincare information. Here are the claims worth ignoring.

"If you don't burn, you haven't damaged your skin." A tan is itself a response to UV damage — it indicates skin cells have already been affected. Avoiding sunburn matters, but tanning is not harmless.

"A base tan protects your skin." A base tan offers very little protection and does not make further UV exposure safe.

"It's cloudy, so sunscreen isn't necessary." Cloud, cool temperatures and winter conditions are unreliable indicators of UV levels. Thin or scattered cloud does little to reduce UV. Check the UV Index instead.

"Sunscreen means you can stay outside all day." Sunscreen reduces UV exposure significantly but does not eliminate it — SPF 50 filters around 98% of UVB, not 100%. It should not be used to extend time in the sun, and should be combined with a hat, clothing, shade and sunglasses.

"High SPF only needs to be applied once." Sunscreen is lost through sweating, swimming, towel drying and normal activity. It needs to be applied generously and reapplied every two hours, more often if you are swimming.

"UV through a window can't damage your skin." A substantial proportion of UVA passes through ordinary glass. Sunburn is unlikely, but people who spend long periods driving or working beside windows will accumulate exposure that contributes to premature ageing and other skin damage.

Check the evidence before believing what you read

Social media can make a single study, an individual's experience or a dramatic headline appear far more authoritative than it is. Before changing your sun-protection habits, consider who produced the information, whether the claims have been reviewed by relevant experts, how recent they are, and whether reputable health organisations agree.

What should we do?

For Australians, the approach is simple: check the UV Index. Whenever it reaches 3 or above, combine protective clothing, SPF 50 or higher broad-spectrum water-resistant sunscreen, a broad-brimmed hat, shade and sunglasses.

Remember that UV exposure is cumulative and often gives no warning signs at the time. Protecting your skin consistently reduces the damage that builds up over a lifetime, and with it the risk of skin cancer.

If you notice a new or changing mole, a sore that does not heal, or any other unusual change to your skin, arrange an assessment with a qualified healthcare professional.

About DermScreen

DermScreen was founded by a team of dermatologists concerned about the high prevalence of skin cancer in Australia. The clinics use skin examinations together with digital imaging technology to assist with the assessment and monitoring of skin lesions. Where appropriate, patients can also be referred for specialist dermatological review.

DermScreen has clinics in Epping, Bondi Junction, Randwick and Sydney CBD.