How to stop a bite itching

Cold first, then an antihistamine, then hydrocortisone cream if it is still bothering you. Ten minutes of a cold pack in the first hour does more than anything applied on day three, and keeping nails short prevents the complication that actually matters.

What works

Cold. A cold pack or a cloth-wrapped ice pack for ten minutes reduces both the swelling and the itch signal. It is the most effective single thing in the first hour, and it is free.

Oral antihistamine. A non-drowsy antihistamine during the day, or a sedating one at night if the itch is keeping someone awake. This works on the histamine that causes the itch rather than on the skin surface.

Topical hydrocortisone (1%). Useful for persistent itchy bites. Thin layer, twice a day, a few days — not on broken skin and not long-term on the face.

Covering it. For children, a simple plaster overnight prevents the scratching that turns a bite into an infection. Unglamorous and very effective.

What does not work

• Nail polish, bleach or petroleum jelly to "suffocate" a chigger. The mite left hours earlier.
• Heat pens and folk remedies — mixed evidence at best, burns at worst.
• Topical antihistamine creams, which can cause contact sensitivity and work less well than the oral form.
• Scratching hard enough to hurt. It relieves itch for seconds by substituting pain, then makes it worse and breaks the skin.

Why the itch outlasts the mark

The reaction is to proteins in the insect's saliva, and clearing them takes days. In sensitised people — anyone who reacts strongly to bed bugs, chiggers or no-see-ums — the itch commonly runs one to two weeks after the bump has flattened.

When itch is a signal, not a symptom

Itch that is symmetrical, in finger webs and at the waistline, and dramatically worse at night, with other household members itching too, points to scabies rather than to bites — and that needs prescription treatment, not soothing cream.