Sunscreens will only give the claimed level of protection if they are applied generously. In Australia, sunscreens are measured using the SPF rating system, which is always listed on the label. SPF 50+ is the highest.
The product label must also indicate if the product is water resistant – and for how long. Many products are water resistant for 2 hours – the maximum water resistance claim allowed is 4 hours.
Note: Don’t use sunscreen that is past its expiry date – the chemicals may have broken down and will not give any protection against the sun. Similarly, don’t store sunscreens in a hot car – as this may make them less effective.
Insect repellents containing DEET may reduce the SPF effectiveness of sunscreen by a third. There are combination sunscreen and insect repellent products, however, it’s not generally recommended to use these combination products, as sunscreen needs applying more frequently than insect repellent.
Chemical sunscreens absorb the harmful ultraviolet light to protect the skin against sunburn. Because different chemicals have varying profiles of UVA and UVB absorption, a combination of chemicals is usually used in sunscreens. Chemical sunscreens should be applied at least 20 minutes before sun exposure, to make the chemicals — cinnamates, octocrylene and the less commonly used para-aminobenzoic acid (PABA) derivatives — more active on the skin. They need to be reapplied at regular intervals. Some people are allergic to some of the chemicals used in chemical sunscreens.
Physical sunscreens – also known as mineral sunscreens – deflect and scatter UV radiation rather than absorb it. Some of them appear white or milky after applying to the skin.
Zinc oxide or titanium dioxide are the active ingredients used in physical sunscreens. These 2 ingredients are usually included in the form of micronised mineral particles – sometimes they are so small as to fall into the category “nanoparticles”. In Australia at present there is no requirement to declare the particle size of the active ingredients, so sunscreens with nanoparticles won’t be labelled as such. The controversy over nanoparticles centres around whether they penetrate the outer layer of the skin to reach living cells in the deeper tissues. At the moment, the Therapeutic Goods Administration say that the evidence shows the particles remain on the surface of the skin.
Broad spectrum physical sunscreens usually use a combination of zinc oxide and titanium dioxide. Physical sunscreens are usually a better choice for people who have had allergic reactions to chemical sunscreens. They may also be safer for children.
Sunscreens for babies and children
The Australasian College of Dermatologists does not recommend chemical sunscreens are used regularly or widely in young babies. Their skin absorbs more of the chemical than adults. Physical sunscreens labelled for sensitive skin are usually better for children and babies. Look for those which have been dermatologically tested – many brands have a baby or toddler formula.
You can patch test a new sunscreen on a small area of your child’s skin, such as inside the elbow to check for any skin reaction.
In any event, the Cancer Council recommends that infants under 12 months are not purposely exposed to direct sun when UV levels are 3 and above.
Treatment of sunburn
If the skin has reddened and also feels hot to touch it can be treated at home and should heal in a few days. Not many cases of sunburn require medical attention and there are a number of things that you can do to help treat mild sunburn:
- Apply cold compresses or immerse the affected area in cool water.
- Calamine lotion may be applied to itchy areas. This may not be appropriate if your skin is dry — an oily calamine lotion is an alternative. Ask your pharmacist or doctor for advice.
- Apply a moisturising cream or lotion to the affected areas; however, you should avoid salves or butter. Aloe vera gels and lotions can be soothing.
- Drink plenty of water, but avoid alcohol which can dehydrate the skin even further.
- If blistering occurs, lightly bandage or cover with gauze to prevent infection. Do not break the blisters as this will slow the healing process and increase the risk of infection.
- In cases of severe pain or discomfort pain relief such as paracetamol or ibuprofen may be taken.
- Wear loose, soft clothing to avoid irritation of the burned skin.
However, skin that has blistered or is swollen with considerable localised pain is considered to be a first-degree burn and will possibly need medical treatment. Care needs to be taken in this case if the sunburn is accompanied by fever, nausea and dehydration, as this will need medical treatment.