Itch from insect bites

After a mosquito, midge or jellyfish sting the skin answers with a weal, redness and itch: histamine dilates vessels and irritates nerve endings. An ordinary reaction passes in a few days, and the job is not to scratch so that infection does not get in. Cold, topical products and an oral antihistamine for severe itch all help. Rapidly spreading swelling, hives all over the body or difficulty breathing call for emergency care.

ICD-10 T63.41 drug

Also known as: Insect bite reaction

Drugs used for this condition

CDimetindeneAdd-on therapy · Antihistamine for topical useDimetindene gel is the first thing people grab in a Spanish pharmacy after a mosquito summer: Fenistil, Dermapic, Dimestil. The AEMPS ficha técnica frames the indication broadly: relief of itch in dermatoses, urticaria, insect and marine animal bites, in adults and children from 1 month, applied 2 to 4 times a day. The evidence base for topical antihistamines is modest. The experimental work by Lever and Marks (Skin Pharmacol 2009) showed that dimetindene gel reduces itch and the weal and flare reaction in models of artificially induced pruritus – that confirms the mechanism but does not replace clinical trials on real bites. In practice the gel relieves through antihistamine action and cooling, while a strong reaction calls for an oral antihistamine. The ficha asks to avoid sun on treated areas.

How to read tiers A–F

Evidence tiers belong to the drug-indication pair, not to the drug as a whole: the same substance can be A for one condition and F for another.

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit