Topical Corticosteroids Potency and Use
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Direct answer
Topical corticosteroids are graded into four potency classes, from very potent to mild, and the core prescribing skill is matching strength to the site and the disease. Clobetasol propionate 0.05 per cent is the strongest commonly used agent, while hydrocortisone 1 per cent is mild and preferred for the face, flexures and infants. Prolonged use over large areas or under occlusion risks skin atrophy and suppression of the hypothalamic-pituitary-adrenal axis.
What you must remember
- Potency classes: very potent, potent, moderately potent and mild, with clobetasol propionate 0.05 per cent at the top and hydrocortisone 1 per cent at the mild end.
- Fingertip unit: the amount squeezed from an adult index fingertip, about 0.5 g, which covers roughly two adult handprints or about 2 per cent of body surface area.
- Site selection: the face, genitals, axillae and skin folds absorb more steroid, so mild agents are chosen there, while thick palms and soles tolerate stronger ones.
- Vehicle: ointments are more occlusive and penetrate better than creams of the same strength, so ointments suit dry, thickened plaques and creams suit moist or weeping lesions.
- Local adverse effects: skin atrophy, striae, telangiectasia, perioral dermatitis, steroid acne, hypopigmentation and rebound flare on withdrawal.
- Systemic adverse effects: hypothalamic-pituitary-adrenal axis suppression, Cushingoid features and growth suppression in children, mainly with potent agents used over large areas.
Matching potency to the site and the disease
Eczema on the eyelid and eczema on the thick skin of the elbow need very different steroids, so the prescriber works through a short sequence. Each step keeps exposure proportional to the risk.
- Check the site first: The face, flexures, genitals and eyelids take the mildest effective agent, because potent steroids there cause atrophy and perioral dermatitis.
- Measure the area: Fingertip units estimate how much cream is needed each day, which prevents both under-treatment and an unnecessarily large systemic dose.
- Choose the vehicle: An ointment suits dry, lichenified plaques, a cream suits moist areas, and a lotion or gel suits hairy regions such as the scalp.
- Step down once controlled: After the acute flare settles, the potency is reduced or the steroid is used intermittently, which limits atrophy and tachyphylaxis.
- Withdraw gradually: Abrupt cessation of long-term potent use causes rebound flare, so a taper with regular emollients is preferred.
- Treat infection separately: Infected eczema needs an antimicrobial, because a steroid can hide signs of infection and allow spread.
The guiding rule is the lowest effective potency for the shortest effective period.
Where the examiner catches the careless prescriber
Potency questions usually hide a site, age or infection trap.
- Trap: choosing clobetasol for facial eczema because it acts fastest Correct: facial skin is thin and absorbs more steroid, so a mild agent such as hydrocortisone is preferred to avoid atrophy.
- Trap: assuming topical steroids are harmless in infants Correct: infants have a large surface area relative to body weight, so adrenal axis suppression is a real risk with potent or occluded use.
- Trap: treating infected eczema with a steroid alone Correct: the infection needs an antimicrobial, since steroids mask its signs and can allow spread.
- Trap: stopping a potent steroid suddenly after months of use Correct: rebound flare follows abrupt withdrawal, so a gradual step-down is the standard approach.
Frequently asked questions
Which topical steroid is preferred for facial eczema?
Hydrocortisone 1 per cent is commonly preferred for facial eczema because facial skin is thin and absorbs topical corticosteroids more readily. Potent preparations are avoided on the face unless a specialist advises otherwise, since they can cause atrophy, telangiectasia and perioral dermatitis.
What is a fingertip unit in topical steroid prescribing?
A fingertip unit is the amount of cream squeezed from an adult index fingertip, roughly 0.5 g. One fingertip unit covers about two adult handprints, which is around 2 per cent of body surface area, so it helps estimate the quantity needed for a given area.
What systemic effect can topical corticosteroids cause?
Topical corticosteroids can suppress the hypothalamic-pituitary-adrenal axis, especially potent agents applied over large areas, under occlusion or in infants. Suppression can lead to adrenal insufficiency on withdrawal, and Cushingoid features and growth suppression in children are also described.
What is topical steroid withdrawal?
Topical steroid withdrawal is a rebound flare with burning, redness and spreading eczema after abrupt cessation of long-term potent steroid use. It is managed with a gradual step-down in potency, regular emollients and patient education, rather than by restarting the strongest agent.