Water-resistant sunscreen doesn't need reapplying after swimming

What the research found

Health guidance from Australia, the UK and the US agrees. Victoria's child health advice says to reapply every 2 hours, or more often if swimming and sweating, even if the label states 4-hour water resistance. UK advice says to reapply straight after being in water, even if the sunscreen is water resistant. The American Academy of Pediatrics says to reapply every 2 hours, or after swimming or sweating.

Water-resistant labels only describe laboratory testing. Australian rules require these sunscreens to state the tested water resistance time, up to a maximum of 4 hours. A 2025 focus group study with Victorian adults found many wrongly believed a '4 hours water resistant' label meant reapplying only every 4 hours when swimming. Researchers said this confusion needs fixing.

A 2014 randomised trial of 18 volunteers tested sunscreen before and after swimming. It found that putting a cream or lotion on the skin first caused a considerable loss of water resistance. So how you apply it matters too. A 2025 online trial of 3,363 adults found that clearer reapplication information on labels improved people's knowledge of when to reapply.

What it doesn’t mean

• Water-resistant sunscreen is still the type recommended if your child will sweat or be in water. It just isn't a one-application product.
• Sunscreen should not be your child's only protection. Hats, covering clothing and shade matter too, especially around water where UV is reflected.
• Babies under 6 months should be kept out of direct sun, and a healthcare professional should be asked before using sunscreen on them. Test a new sunscreen on a small patch of skin first, and see your pharmacist or GP if a skin reaction occurs.