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Chronic actinic dermatitis


What are the aims of this leaflet?

This leaflet has been written to help you to understand more about chronic actinic dermatitis (CAD). It explains what it is, what causes it and what can be done about it. It also tells you where you can find more information about the condition.

What is chronic actinic dermatitis?

The term ‘chronic actinic dermatitis’ or “CAD” is used to describe a particularly severe form of eczema in which sensitivity to light is the main feature (photosensitivity). CAD is chronic, that is to say it typically persists for a number of years. ‘Actinic’ means “caused by sun” and ‘dermatitis’ (which is another term for eczema) means itchy inflammation of the skin.

What causes CAD?

People with CAD are very sensitive to sunlight. This causes an eczema-like reaction and can happen after as little as 30 seconds of exposure. It often only affects the areas of skin which are directly exposed to the light, and is usually worse in the summer when sunlight is strongest. There can be a delay between the sun exposure and the skin change of several days, so people may not realise that the two are linked. It is not clear exactly why certain people develop this reaction to sunlight. It may be that this is an allergy that is triggered only when light comes into contact with skin.

Other points about CAD:

  • It is more common in men than women

  • It usually starts after the age of 50

  • It may occasionally occur in younger patients with atopic dermatitis

  • It is also associated with a skin allergy to substances other than sunlight in 75% of cases

  • It can affect any racial group

  • It is more common in countries away from the equator

Is CAD hereditary?


What are the symptoms of CAD?

Often the first thing that people with CAD notice is redness or inflammation of the face and hands which can be patchy or general. This may not cause any other symptoms but some may have itching and burning. Others may have swelling, small blisters or scaling and peeling of the skin.

What does CAD look like?

The skin changes are often strikingly limited to sun-exposed areas such as the face, ears, scalp, ‘V’ shaped area of the neck and the chest, forearms and backs of hands. There can be sharp cut-off lines where covered areas meet sun-exposed skin. After some time, the skin becomes thickened, dry and scaly. These changes may persist throughout the winter months but tend to be more severe in the summer. Skin pigmentation may develop, which can be particularly striking in darker skin types.

How can CAD be diagnosed?

Patients with CAD tend to have severe skin disease and are usually referred to their local dermatology service. If the dermatologist suspects CAD they will usually refer the person for light testing.


In order to confirm the diagnosis of CAD light testing is carried out. This painless test involves exposing sun-protected skin on the back to a range of different doses of ultraviolet rays of types A and B, and also to visible light. These tests usually reveal significant photosensitivity to one or more of the wavelengths of these types of light. This helps to establish the diagnosis and may also be useful when planning how best to protect the skin from the activating wavelengths.

Patch testing

Most patients with CAD also have an additional investigation called “patch testing” to see if they are allergic to any chemicals that come into contact with the skin. These chemicals include fragrances, plants, preservatives in creams and even the ingredients in sunscreens. Allergy to a chemical is characterised by a red, spotty skin response under the patch test tape. (For more information see Patch Testing leaflet.)

Can CAD be cured?

No, there is no cure for CAD and many patients with CAD remain sensitive to the sun for several years. About 10-20% of patients will find the problem goes away by itself after a number of years. However, there are measures that can be done to relieve the symptoms of this condition and lessen the effect of light.

Self Care (What can I do?):


The most important thing to do is to protect the skin from the sun, even on dull days. This can be done by staying indoors, particularly when the sun is at its brightest (between 11am and 3pm). It is also essential to cover the skin as much as possible when outside. Clothing is good at blocking the sun’s rays. Some people use hoods, hats, visors and cotton gloves. Protecting the skin from the sun may improve the condition and may stop it worsening.

If patients work outdoors or have hobbies which involve being outside, they may need to try and adjust their lifestyle where possible to minimise sun exposure. Watching television or a computer screen is safe. Some people may need to apply special photoprotective window films to the windows of their car and home in order to block out UVA and UVB light. These protective films may stop working and need replacing after about five years. Some car manufacturers offer UV protective glass as standard or as an optional extra, however most car windows do not block UV light. Your dermatologist or a patient support group may be able to advise you about suppliers of UV protective film.

Appropriate sunscreens should be used and some of the sunscreens available in the shops might be either weak or could be an additional causal factor in the skin reaction. An example of such tinted reflectant sunscreens, which can be mixed to match the individual skin colour, is available on prescription from Tayside Pharmaceuticals (see below for details).

Avoidance of allergy

If you prove to be allergic to certain substance/substances during patch testing, they should be very carefully avoided.

Vitamin D advice

The evidence relating to the health effects of serum Vitamin D levels, sunlight exposure and Vitamin D intake remains inconclusive. Avoiding all sunlight exposure if you suffer from light sensitivity, or to reduce the risk of melanoma and other skin cancers, may be associated with Vitamin D deficiency.

Individuals avoiding all sun exposure should consider having their serum Vitamin D measured. If levels are reduced or deficient they may wish to consider taking supplementary vitamin D3, 10-25 micrograms per day, and increasing their intake of foods high in Vitamin D such as oily fish, eggs, meat, fortified margarines and cereals. Vitamin D3 supplements are widely available from health food shops.

How can CAD be treated?

Creams and ointments

Usually, lots of moisturiser as well as steroid creams will need to be used on the affected areas. There are other creams which are not steroids that can sometimes help, such as tacrolimus and pimecrolimus. These creams do not cure or prevent the inflammation, but they can reduce it significantly.

Desensitising light therapy

Depending on how severely the skin is affected, the dermatologist may prescribe some ultraviolet light treatment. For some people this can desensitise the skin to light, or ‘toughen’ it up so that they react less when exposed to the sun again.

Immune-suppressing tablets

Occasionally, people with severe CAD require tablets to control their skin disease. This could be a steroid (prednisolone) tablet or another immune system suppressing tablet such as azathioprine or ciclosporin. Patients would need to be carefully monitored in the clinic if they were prescribed these drugs.

Where can I get more information about CAD?

Web links to detailed leaflets:

Other information:

Tayside Pharmaceuticals

Ninewells Hospital

Dundee, DD1 9SY

Tel: 01382 632052

For details of source materials used please contact the Clinical Standards Unit (

This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: its contents, however, may occasionally differ from the advice given to you by your doctor.

This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel






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