Author: Dr Roy Palmer
A common type of sun damage is called actinic keratosis (also known as solar keratosis). An actinic keratosis is a rough pink patch on the skin. They are most common on the face and hands of fair-skinned people who have had a lot of sun exposure during their life. A closely related condition is called Bowen’s disease; it can be thought of as a thick actinic keratosis. Rarely actinic keratoses and Bowen’s disease can develop into a type of skin cancer called SCC. They respond to treatment with liquid nitrogen, or creams such as Efudix. Liquid nitrogen can be highly effective; after the treatment the area becomes redder and may blister, and these symptoms resolve after approximately one week. Just one treatment will often cure an actinic keratosis. Efudix cream is usually used twice a day, for three weeks, and it results in a lot of inflammation, which gradually resolves over about 1-2 weeks of the treatment finishing. It is fairly effective and is good for ‘field change’ of actinic keratosis (ie. when a large area is affected). Solaraze is a cream that causes much less inflammation than Efudix (often no inflammation at all) but unfortunately it often doesn’t result in much improvement, so I do not usually suggest trying it.
Another type of sun damage is a solar lentigo (the plural is solar lentigines). A solar lentigo is a brown patch on the skin. They are common on the face and hands. They are usually harmless but it is important to check that a brown patch is not a pre-cancerous lesion called lentigo maligna, or a melanoma.
Avoiding excessive sun exposure involves staying out of the sun, wearing suitable clothing and using sunscreen with a high SPF (eg. 50). SPF stands for ‘sun protection factor’ and is the ratio of how much ultraviolet B (=UVB) your skin can be exposed to with the sunscreen on, versus without it, before sunburn develops. So an SPF of 10 means you can be exposed to the sun for 10 times as long. However, most people only apply sunscreen one-third as thickly as in the studies that measure SPF, so most people only get a third of the protection they are expecting. Added to that, the sunscreen will be rubbed off and sweated off over a few hours, so the ‘real’ SPF obtained is much below the official SPF. In the UK the maximum SPF that manufacturers are allowed to claim is 50+, meaning greater than 50. The SPF is only a measure of UVB protection; UVB has generally been thought to be more important than UVA. However, it is best to use a sunscreen which also has good UVA protection. There isn’t a universally agreed measure of UVA protection, but the commonest is the star system; in this, five stars is the highest protection available.
If you are avoiding the sun to a high degree then you should consider taking oral vitamin D supplements.