It's important to use sunscreen (as well as follow other sun smart measures) year-round, but many of us don't pay that much attention to it until spring or summer hits.
But is the half-used tube at the bottom of your beach bag still effective at protecting your skin from harmful UV rays? Or does sunscreen expire?
How long does sunscreen last?
In Australia, all sunscreens are regulated by the Therapeutic Goods Administration (TGA), and will generally last between two to three years.
They're also required to be labelled with an 'expiry' or 'use-by' date on the packaging, so you don't have to remember when exactly you bought them. (Although you may have to do a little searching – the expiry dates aren't always easy to spot.)
Sunscreens must have an 'expiry' or 'use-by' date on the packaging, but some are easier to read than others.
Can I still use expired sunscreen?
It's not recommended.
"Past its expiry, ingredients within the sunscreen may separate, affecting the distribution of active ingredients across the skin and overall protection from UV radiation," says Heather Walker, Chair of Skin Cancer Committee, Cancer Council Australia.
"This means it will not reach its stated SPF and you'll be left unprotected.
"The Cancer Council does not recommend using expired sunscreen. If a sunscreen is past its use-by date, dispose of it safely and buy a new sunscreen."
How to store sunscreen
Sunscreen should be kept out of direct sunlight or other heat sources, and needs to be stored below 30°C to remain effective, regardless of the expiry date. (When outside in the hot Aussie summer, you may find it helpful to keep sunscreen in the shade or wrapped in a towel.)
"If sunscreens are left in high temperatures for extended periods of time (for example, in the glove box of a car in the heat) the ingredients will begin to separate, leaving a gritty, lumpy or watery consistency that may affect how it is applied to skin, as well as the effectiveness of its UV protection," says Walker.
But that doesn't mean you should store sunscreen in the fridge. Refrigeration "may set some ingredients in the sunscreen," says Walker, "causing it to thicken and make it difficult to apply."
Check the consistency
Even if it has been stored correctly, if you haven't used your sunscreen in a while it's important to check the consistency – as that may indicate whether or not it's gone bad ahead of time.
"If a sunscreen looks or feels different to how it did when you first purchased it, it can be an indication that the sunscreen should not be used," says Walker.
How much sunscreen do I need?
Many Australians don't apply enough sunscreen, which substantially reduces its effectiveness.
To ensure you're properly covered, you need to apply seven teaspoons:
- 1 teaspoon for face, neck and ears
- 2 for the torso (front and back)
- 2 for the arms (1 each arm)
- 2 for the legs (1 each leg).
Not applying it often enough (every two hours), not reapplying after swimming or exercising, and inadvertently rubbing it off on clothing, towels and so on can also reduce its effectiveness.
You need more than sunscreen to be sun-safe
Sunscreen is just one line of defence against the sun's ultraviolet (UV) radiation.
For the best protection, the Cancer Council recommends you slip (on clothing), slop (on sunscreen at least 30+), slap (on hat), seek (some shade) and slide (on some sunglasses).