Treating simple bug bites isn't usually necessary and there's little evidence to support doing so, a review warned.
Aside from anaphylaxis and atopic eczema flare-ups, insect bites typically resolve on their own, according to an unsigned article in the April issue of Drug and Therapeutics Bulletin.
The best management for mild local reactions may be simple first aid with a cold compress to manage the itching, pain, and swelling, as well as cleaning the affected area to avoid secondary infection, authors of the review suggested.
Although antihistamines, topical corticosteroids, analgesics, antiseptics, cooling agents and other over-the-counter products are available and sometimes advocated, "there is a lack of evidence for the efficacy of these treatments and, in general, recommendations for treatment are based on expert opinion and clinical experience," the reviewers explained.
Oral antihistamines help reduce immediate reactions that cause itching but don't do much against delayed reactions to bites, based on the few small double-blind studies available, which variously tested loratadine, cetirizine (Zyrtec, Alleroff, Aller-Tec), ebastine (not available in the U.S.), and prophylactic levocetirizine (Xyzal).
Topical antihistamines generally aren't recommended. They are only marginally effective, can sometimes cause sensitization, and shouldn't be used for more than 3 days, the British National Formulary notes.
Topical corticosteroids, though, are recommended despite the fact that no studies have supported their use specifically for bug bites and should be used for atopic eczema triggered or exacerbated by bites, according to the review.
The corticosteroid cream should be applied sparingly and for a short duration to minimize side effects, but shouldn't be used on infected bites or on the face or on skin broken by scratching.
Oral corticosteroids are only recommended for severe local reactions or systemic reactions, again despite no evidence in the literature to support this practice.
"In view of the potential adverse effects, the lowest effective dose should be used for the shortest time," the review authors cautioned.
Ibuprofen and other analgesics are recommended for painful bites, but the British National Formulary cautions that topical anesthetics like lidocaine and benzocaine are only marginally effective and occasionally trigger sensitization.
Anti-itch preparations are of dubious value, according to the review.
One study found crotamiton (Eurax) -- although recommended on British guidelines -- to be no better than lotion without the compound. Calamine lotion is not recommended for treating bug bites.
Counter-irritants may work better: One trial found household ammonia (dilute ammonium solution) to at least partially relieve itching, burning, or painful mosquito bites for up to 90 minutes in all treated patients, which was much better than placebo.
Antibacterial treatment isn't necessary for simple insect bites, although secondary infections may need oral antibiotics in accordance with local guidelines, the review noted.
For more serious cases, like large local skin reactions with redness and swelling over 10 cm in diameter, referral to an allergy clinic should be considered.
Severe systemic reactions should be treated urgently like anaphylaxis, with adrenaline and admission to the hospital.
Management of bites from ticks, mites, and lice wasn't covered in the review.