Beauty Clinic: Decoding sunscreen labelling

Q. I am so confused about the labelling on sunscreens. Could you explain what it all means and what to look for? A. You are among the majority of the population. A survey of 2,000 adults carried out for the Royal Pharmaceutical Society revealed a high level of confusion about the different ratings.

There are two types of UV radiation that sunscreens are formulated to defend against. The SPF (sun protection factor) rating only applies to UVB, which is the main cause of sunburn.

Protection against UVA rays, which penetrate more deeply and is linked to skin ageing, is usually indicated by a star system, with up to five stars.

Both UVA and UVB rays can cause skin cancer, including malignant melanoma, which is potentially fatal. The rates of this disease have risen steeply in the last few decades.

When buying a sunscreen you should look for the letters UVA inside a circle on the label, which indicates that the product has a guaranteed minimum level of UVA protection. Some brands such as Boots still use a nought to five star rating to indicate the level of UVA protection.

The consensus is that SPF 15 or more is enough for a normal working day in the UK, i.e. not sunbathing. But remember that UV rays can penetrate the clouds and through glass. If you are in a sunnier climate, choose a water resistant or waterproof SPF30 with UVA protection. Applied correctly (more below on this), this will give you 97 per cent protection against UVB. A higher SPF will only give you one per cent more protection at the expense of more potentially toxic chemicals, according to experts.

SPF labelling in the EU is categorised as follows:

SPF 14.9 or below = low protection

SPF 15 - 30 = medium protection

SPF above 30 = high protection

SPF above 50 = very high protection

Always look for products that are photo-stable, which means the chemicals are stable in the sunlight. And check the expiry date: do not use last year’s sun preps.

Laboratory tests for sun protection products use liberal amounts and that is what the SPF figures are based on. So skimming a little bit on your face and body will not give you the protection on the label. Always apply plenty, at least every two hours (and always after swimming or perspiring heavily), and don't rub in. In an ideal world, pop on a layer half an hour before going out in the sun and then apply another before exposing your skin. (But don't think that applying two layers of SPF15 gives you an SPF30, it’s still 15…)

One other area of confusion today is that many moisturisers and foundations contain an SPF. While this may be useful for running around on an ordinary day, it will not protect you if you are sunbathing.

Finally, dermatologists warn that it is vital to avoid sunbed use. They produce much larger amounts of UVA than the sun. Experts including consultant dermatologist Professor Nick Lowe say categorically we should not use them. End of. (See Professor Lowe’s recommendations here.)