Guidance

Summary of the evidence

Summary of the evidence

This is a summary of the evidence. For full details, see the evidence review.

The evidence included:

  • 1 randomised controlled trial in adults with extensive cellulitis caused by an arthropod bite (Friedland et al. 2012)

  • 1 systematic review of double-blind crossover randomised controlled trials of oral antihistamines in people with uninfected mosquito bites (Foex et al. 2006)

  • 2 double-blind crossover randomised controlled trials of oral antihistamines in people with uninfected mosquito bites (Karpinnen et al. 2006 and Karpinnen et al. 2012)

  • 1 retrospective study (Dyachenko and Rozenman 2006) of treatments in people with an uninfected bite (confirmed or presumed to be caused by a brown recluse spider).

Randomised controlled trial evidence was only identified for the effectiveness of oral antihistamines in adults and children with mosquito bites and for intravenous antibiotics in adults with an infected arthropod (of undefined species) bite. Only 1 of the randomised controlled trials included people with a secondary infection of their bite and this was a subgroup of people with an infected arthropod bite from a larger trial.

No evidence was identified for antibiotics in children and young people.

Antibiotics for infected arthropod bites in adults

Based on clinical response at day 3, there was no statistically significant difference in the clinical effectiveness of intravenous ceftaroline compared with intravenous vancomycin plus intravenous aztreonam (Friedland et al. 2012) in adults with extensive cellulitis caused by an arthropod bite. No adverse effect data were reported.

Oral antihistamines for uninfected mosquito bites in adults

Cetirizine 10 mg once or twice daily compared with placebo

There was no statistically significant difference in median mosquito bite lesion size at 10 minutes, 60 minutes, 12 hours or 24 hours with cetirizine compared with placebo. In 2 studies, there was a statistically significant difference in median mosquito bite lesion size at 15 minutes compared with placebo (but no statistically significant difference was seen in a third study).

There was no statistically significant difference in pruritus after mosquito bite exposure at 10 minutes, 30 minutes, 90 minutes, 24 hours, 48 hours, 5 days or 7 to 10 days with cetirizine compared with placebo. However, there was a statistically significant reduction in mean or median pruritus scores at other time points: 15 minutes, 60 minutes, 12 hours, and at days 3, 4 and 6.

There was no statistically significant difference in adverse effects (mild to severe sedation, headache, emesis or arthralgia) at follow up.

In 1 study, 7 of 9 people preferred cetirizine 10 mg twice daily (1 preferred placebo and the other had no preference).

Levocetirizine 5 mg once daily compared with placebo

There was a statistically significant reduction in both median mosquito bite lesion size and median pruritus scores at 15 minutes, and in delayed bite lesions at 24 hours.

There was no statistically significant difference in adverse effects (mild to moderate somnolence) at follow up.

Loratadine 10 mg once daily compared with placebo

There was no statistically significant difference in median mosquito bite lesion size or median pruritus scores at 15 minutes.

There was no statistically significant difference in adverse effects (mild to moderate sedation) at follow up.

Rupatadine 10 mg once daily compared with placebo

There was a statistically significant difference in median mosquito bite lesion size at 15 minutes, but no statistically significant difference in delayed bite lesion size at 24 hours. There was also a statistically significant reduction in median pruritus scores at 15 minutes but no statistically significant difference for delayed bite reaction pruritis at 24 hours.

Adverse effects (sedation) were statistically significantly increased at follow up.

Antihistamines for uninfected mosquito bites in children

Loratadine 0.3 mg/kg once daily compared with placebo

There was a statistically significant reduction in median bite lesion size at 15 minutes and 24 hours but no statistically significant difference at 2 hours and 6 hours. There was also a statistically significant reduction in median pruritus score at 15 minutes.

There was no statistically significant difference in adverse effects (mild gastrointestinal pain and diarrhoea) at follow up.

Treatments for uninfected brown recluse spider bites

A single-centre retrospective study (Dyachenko and Rozenman 2006) reported data for 52 people with an uninfected bite that was confirmed or presumed to be caused by a brown recluse spider. The study included people aged 9 to 66 years; results were not broken down by age.

All patients had prophylactic antibiotics (92.3% had cefalexin; no further details given), rest, cold compression and elevation. Most patients (92.3%) had prednisolone and an antihistamine (no further details given), and 21 patients (40.4%) had a non-steroidal anti-inflammatory drug. All the outcomes were assessed as being of very low quality.

The authors concluded that none of the treatments prevented necrotic lesions, and their role in time to healing and length of hospital stay was unclear.

See the evidence review for more information.