What topical steroids actually do

Eczema is at heart an inflammatory condition. Your skin's barrier is weaker than it should be, irritants and allergens slip through, and the immune system responds with redness, heat, swelling and intense itch. Topical steroids — creams, ointments and lotions applied directly to the skin — work by dampening that immune response at the site. They calm the inflammation, which in turn eases the itch and gives the skin a chance to repair.

It helps to be clear about what they are not. They are not a cure for eczema, and they do not repair your skin barrier or replace lost moisture. That is the job of emollients, used generously and every day. Think of steroids as the fire brigade and emollients as the fire prevention: you need both, and one does not cover for the other.

Why the strength matters so much

Topical steroids in the UK come in four potency groups, from mild to very potent. Mild products such as hydrocortisone 1% are often available over the counter. Moderate options include clobetasone butyrate. Potent ones include betamethasone valerate and mometasone furoate. Very potent products such as clobetasol propionate are usually reserved for stubborn, thickened areas and are prescribed under close supervision.

Matching the strength to the site and the severity of the flare is the single most important prescribing decision. Skin thickness varies enormously across the body, so the same cream can behave very differently in different places.

• Face, neck, armpits, groin and skin folds: thin skin absorbs more, so a mild or moderate steroid for a short period is usually enough.
• Arms, legs and trunk: moderate to potent steroids are commonly used for a week or two.
• Palms, soles and thick, lichenified plaques: these areas resist absorption, so a potent steroid may be needed to get on top of the inflammation.
• Children: generally start lower and step up only if needed, because a child's skin surface area relative to body weight is larger.

Under-treating is a common and frustrating problem. A weak steroid used on a stubborn flare may simply fail, leading to weeks of itch, poor sleep and escalating misery — and eventually a stronger product used for longer than if you had started appropriately.

Getting the amount right: the fingertip unit

Most people apply far too little. The fingertip unit (FTU) is a simple, reliable measure: squeeze a line of cream from the tip of your adult index finger to the first crease. That is one FTU, roughly 0.5g, and it covers an area about the size of two flat adult palms.

• One hand (front and back): 1 FTU
• One arm, including the hand: 3 FTU
• One leg, including the foot: 6 FTU
• Face and neck: 2.5 FTU
• Front of trunk: 7 FTU
• Back of trunk, including buttocks: 7 FTU

Children have smaller hands, so the FTU is based on their finger size. Your GP, practice nurse or pharmacist can show you exactly how much to use for each area — it is worth asking.

Using them responsibly day to day

Apply a thin layer only to inflamed skin, usually once or twice a day as prescribed. Smooth it in the direction the hair grows rather than rubbing vigorously. Wash your hands afterwards unless your hands are the area being treated. Do not apply steroid to broken, infected or weeping skin — crusting, golden scabs or a new fever need a review, as you may need an antibiotic or antiviral alongside.

Most flares settle within three to seven days. A useful rule is to continue for around 48 hours after the skin looks and feels normal, then stop. Stopping abruptly the moment things improve can trigger a quick rebound. For people who flare repeatedly in the same spots, some clinicians recommend proactive maintenance — applying a mild or moderate steroid to known trouble areas twice a week, alongside daily emollients.

Steroid creams work best alongside other basics:

• Use plenty of emollient — most adults need 250g to 500g a week, and children similar amounts.
• Leave around 20 to 30 minutes between emollient and steroid so the steroid is not diluted.
• Avoid known triggers such as harsh soaps, fragranced products, overheating and scratchy fabrics.
• Keep fingernails short and consider cotton gloves or bandages at night if scratching is severe.

Side effects and steroid phobia

Prolonged, uninterrupted use of potent steroids can cause skin thinning, stretch marks, visible small blood vessels and, less commonly, absorption into the body that affects hormone balance in children. These risks are real but are mainly linked to strong products used over large areas for many weeks without a break.

Used correctly — the right strength, on the right site, for the right length of time — the risks are small. Unfortunately, fear of steroids ("steroid phobia") is widespread and often leads to under-treatment, which stretches flares out, disrupts sleep and can end with more steroid being used overall. If you are worried, say so. Your pharmacist or GP would far rather talk it through with you than have you struggle on alone.

Working with your clinician

Ask for a written plan that names each product, the site it is for, how often to use it and how long to continue. Request a review if the skin has not improved within one to two weeks, if flares are becoming more frequent, or if you are needing steroid most days. Flaring that never quite settles sometimes signals an infection, a contact allergy or a different diagnosis altogether.

Useful questions to ask at your appointment:

• Which strength is this, and where exactly should I use it?
• How many days should I use it before stopping?
• What should I do if it does not work or comes straight back?
• How much emollient should I be using each week?

Topical steroids remain one of the most effective, best-studied treatments we have for eczema. Used thoughtfully and with good guidance, they clear flares quickly, protect sleep and school and work, and let your emollients do their quieter, longer-term job.