Little evidence to prove insect-bite remedies work
There is little evidence that over the counter remedies for simple insect bites actually work, and in most cases, no treatment at all will suffice, concludes an evidence review in the April Drug and Therapeutics Bulletin (DTB).
In the UK, midges, mosquitoes, flies, fleas and bedbugs account for most of the insects that bite their victims in search of a blood meal.
The saliva they inject can cause a reaction. This may prompt an infection, an eczema flare-up, or anaphylactic shock in the most serious cases, and these clearly warrant appropriate treatment, says DTB.
But in many cases, the reaction is mild, and a range of over the counter remedies is available to deal with the resulting itching, pain and swelling, and secondary problems caused by scratching.
Although antihistamine tablets are widely recommended to quell the itching associated with insect bites, there’s not much evidence to back this up, says DTB. And none of the products used in the studies that have been done have been licensed for use in the UK.
Steroids (creams and tablets) are recommended for itching and inflammation, although there is no actual evidence to support their use, says DTB, except for people with eczema.
And DTB goes on to warn that steroid based creams should be used only sparingly and not on the face or broken skin, which typically accompanies vigorous scratching.
Similarly, although steroid tablets are recommended for severe localised and systemic reactions, there isn’t any evidence to back up that approach either.
Creams containing painkillers/anaesthetics, such as lidocaine, benzocaine, or combined with antihistamines and antiseptics, are only "marginally effective and occasionally cause sensitisation," says DTB.
There is no hard evidence for the use of the anti-itch preparation Crotramiton, and the drugs bible, the British National Formulary (BNF), notes that "it is of uncertain value," says DTB.
While there is some evidence to suggest that dilute ammonium solution (counter-irritant) may help relieve itching and/or burning, there is little evidence for antiseptics or astringents.
"There is little evidence for the efficacy of treatments for simple insect bites. The symptoms are often self limiting and in many cases, no treatment may be needed," concludes DTB.