Sunscreen should not be your only protection from the sun. Other ways of being sun smart include:
- limiting your exposure to direct sun
- seeking out shade
- wearing a hat, sunglasses and appropriate clothing.
How to apply sunscreens
Research shows that sunscreens are effective when applied frequently and liberally. How much you need to apply and how often you need to reapply depends on the type of sunscreen and your activity.
Don't assume that all sunscreens are the same and have the same instructions for use. It may surprise you how much sunscreen is required for each limb and how often you may need to reapply. The instructions for proper use of a sunscreen are always written on the label and should be followed.
The Australasian College of Dermatologists recommends that the use of sunscreens should be minimised for infants below 6 months of age due to the sensitive nature of newborn and infant skin. If sunscreen must be used on infants under 6 months of age, a healthcare professional should be consulted.
Lotions
At least 1 teaspoon of sunscreen (approximately 5 ml) should be applied to each area (arm, leg, back, etc.). The same amount should be reapplied at least every 2 hours, especially after swimming or towelling. More frequent application is required when undertaking activities in the water or that cause perspiration.
Aerosols
When using aerosol cans or sprays, you should consider how much of the spray can miss the skin and apply more to accommodate.
Aerosol sunscreens are mixed with propellant, so they are more dilute than an equivalent volume found in a sunscreen lotion. This means you may have to use more compared to a lotion or cream to achieve the same coverage.
Adults should apply 35 - 40 ml of sunscreen to the whole body in a single application to achieve adequate protection. The average can of aerosol sunscreen contains approximately 90 - 100 ml of sunscreen formulation, excluding the propellant. This means that approximately 1/3 of a can of aerosol is required for a single application to cover the whole body.
Aerosols should not be applied in windy conditions as application under even light wind (10 kph) and moderate wind (20 kph), can result in the majority of the application missing the skin compared to application when there is no wind.
Aerosols should also not be sprayed directly on to the face to avoid adverse effects from accidental inhalation.
Common side effects of sunscreens
The most common side effects from sunscreens reported to us are local skin reactions, so it is a good idea to test sunscreens on a small patch of skin before first use, especially in young children or when changing to a new sunscreen.
The test can be performed by applying some sunscreen on a small area of skin on the inner forearm and monitoring for any changes to the condition of the skin. If a skin reaction develops ask your pharmacist or healthcare practitioner for advice on a suitable alternative product.
We cannot give advice about an individual's medical condition. You are strongly encouraged to talk with a health professional if you are concerned about a possible adverse event associated with a sunscreen.
Nanoparticles in sunscreens
A common misconception about sunscreens is that the zinc oxide and titanium dioxide nanoparticles in some sunscreens could be a health risk.
We performed a Literature review on the safety of titanium dioxide and zinc oxide nanoparticles in sunscreens in 2017. When used as directed, these sunscreens do not penetrate deeply into the skin. If these particles do penetrate the skin, the amounts are so small they are unlikely to be toxic. We evaluate all new active ingredients for safety before they can be used in sunscreens.