Empirical therapy for patients with extensive, recurrent or bullous impetigo
For additional aspects of management, see Management of impetigo.
Narrow-spectrum antibiotics active against Streptococcus pyogenes (group A streptococcus [GAS]) and Staphylococcus aureus (ie dicloxacillin and flucloxacillin) are recommended as first-line oral therapy for patients with extensive, recurrent or bullous impetigo and for patients with impetigo who are at high risk of acute rheumatic fever. This is based on data that benzathine benzylpenicillin (a narrow-spectrum penicillin) and trimethoprim+sulfamethoxazole are equally effective for the treatment of impetigoBowen, 2014. When selecting an antibiotic, consider ease of administration and preferences of the patient or carer.
For patients with extensive (more than 2 sores), recurrent or bullous impetigo, useNational Institute for Clinical Excellence (NICE), 2020:
1dicloxacillin 500 mg (child: 12.5 mg/kg up to 500 mg) orally, 6-hourly for 5 days. Stop therapy after 3 days if infection has resolved. For dosage adjustment in adults with kidney impairment, see dicloxacillin dosage adjustment dicloxacillin dicloxacillin dicloxacillin
OR
1flucloxacillin 500 mg (child: 12.5 mg/kg up to 500 mg) orally, 6-hourly for 5 days. Stop therapy after 3 days if infection has resolved. For dosage adjustment in adults with kidney impairment, see flucloxacillin oral dosage adjustment. flucloxacillin flucloxacillin flucloxacillin
Cefalexin enables less frequent dosing and is often preferred to dicloxacillin or flucloxacillin in children, because the liquid formulation is better tolerated. Trimethoprim+sulfamethoxazole is another alternative with these features. Use:
1cefalexin 1 g (child: 25 mg/kg up to 1 g) orally, 12-hourly for 5 days. Stop therapy after 3 days if infection has resolved. For dosage adjustment in adults with kidney impairment, see cefalexin dosage adjustmentcefalexin cefalexin cefalexin
OR
2trimethoprim+sulfamethoxazole 160+800 mg (child 1 month or older: 4+20 mg/kg up to 160+800 mg) orally, 12-hourly for 3 days. For dosage adjustment in adults with kidney impairment, see trimethoprim+sulfamethoxazole dosage adjustmenttrimethoprim + sulfamethoxazole trimethoprim+sulfamethoxazole trimethoprim+sulfamethoxazole
OR
2trimethoprim+sulfamethoxazole 320+1600 mg (child 1 month or older: 8+40 mg/kg up to 320+1600 mg) orally, daily for 5 days1. For dosage adjustment in adults with kidney impairment, see trimethoprim+sulfamethoxazole dosage adjustment.trimethoprim + sulfamethoxazole trimethoprim+sulfamethoxazole trimethoprim+sulfamethoxazole
Consider single-dose treatment with intramuscular benzathine benzylpenicillin, if preferred by the patient or the carer. Use:
benzathine benzylpenicillin intramuscularly2, as a single dose3 benzathine benzylpenicillin benzathine benzylpenicillin benzathine benzylpenicillin
adult: 1.2 million units (2.3 mL)
child less than 10 kg: 0.45 million units (0.9 mL)
child 10 kg to less than 20 kg: 0.6 million units (1.2 mL)
child 20 kg or more: 1.2 million units (2.3 mL).
If a patient develops impetigo while receiving benzathine benzylpenicillin for prevention of recurrent acute rheumatic fever, seek advice from a specialist with expertise in rheumatic fever. Ask the patient about adherence to prophylaxis, and treat with antibiotic therapy for impetigo if it has been more than 7 days since the last dose of benzathine benzylpenicillinRHDAustralia (ARF/RHD writing group), 2020.
For patients who have had a nonsevere (immediate or delayed) hypersensitivity reaction to a penicillin4, use the cefalexin regimen above.
For patients who have had a severe (immediate or delayed)5 hypersensitivity reaction to a penicillin use one of the trimethoprim+sulfamethoxazole regimens above.
If impetigo is not improving, take a skin swab for culture and susceptibility testingNational Institute for Clinical Excellence (NICE), 2020The Australian Healthy Skin Consortium, 2023.