Topical corticosteroids

It is important to use enough topical steroid, as using small amounts continuously often results in the topical steroid not working as well and perhaps more being used in the long term.

Topical steroids should be applied with clean hands in a thin layer so that the skin just glistens. It can sometimes be difficult to judge how much steroid to use – there are guidelines on the amount required to cover body areas that are affected by eczema. These are based on the Finger Tip Unit (FTU), which is the amount of cream or ointment that just covers the end of an adult finger from the tip to the crease of the first joint when squeezed from an ordinary tube nozzle. One FTU is enough to cover an area of skin the size of two adult hands with the fingers together.

Different parts of the body require different amounts of topical steroid. For example, in an adult, one arm will need 3 FTUs while a 4-year-old child will require 1 FTU for an arm and hand. Adjustments will be required if only a small part of the larger area is affected by eczema. Further information is often provided in the leaflet supplied with your treatment, and in our Topical steroids factsheet. Any unused steroid cream or ointment should be discarded. Wash your hands after applying steroids unless there is eczema on the fingers.

In the UK, topical steroid preparations are divided into four categories according to how strong or potent they are. The terms used are ‘mild’, ‘moderately potent’, ‘potent’ and ‘very potent’. The potency of topical steroids is determined by the amount of vasoconstriction (narrowing of the blood vessels) they produce. It also relates to the degree to which the topical steroid inhibits inflammation, and its potential for causing side effects.

It can be difficult for the person with eczema or the parent of a child with eczema to work out the potency of a product, since the labelled percentage of steroid on the packaging does not relate to the potency and may sometimes imply a less potent product. The potency of the topical steroid may be stated in the patient information leaflet (PIL) inside the packaging.

One way of understanding the strength of different steroid preparations is to note that ‘moderately potent’ is twice as potent as hydrocortisone 1%; ‘potent’ is 10 times more potent; and ‘very potent’ 50 times more potent. If you are not sure of the potency of a steroid preparation, ask your pharmacist.

Topical steroids, used appropriately and under supervision, are a safe and effective treatment for eczema. The likelihood of side effects occurring is directly related to the potency of the preparation, where it is being used, the condition of the skin on which it is used and the age of the person concerned. Pregnant women should consult a healthcare professional regarding the advisability of continued use of their usual topical steroid preparation. All these factors will be taken into consideration when a prescription is given to treat eczema.

If used over long periods of time, topical steroids can thin the skin, making it appear transparent, fragile and susceptible to bruising; blood vessels may become more prominent, and the skin can lose its elasticity, developing ‘stretch marks’. Other possible side effects include increased hair growth of very fine hair and perioral dermatitis (i.e. a spotty rash around the mouth). However, it should be stressed that these effects usually only occur when potent steroids have been applied for a long period of time, either to the face or to covered parts of the body such as the flexures.

Skin thinning can also occur when steroids have been applied under occlusion (e.g. under bandages or gloved hands). For these reasons, topical steroid use is limited to short periods of time under the supervision of a doctor or nurse.