Can Co-amoxiclav Cause Henoch-Schönlein Purpura?
Yes, co-amoxiclav (amoxicillin/clavulanic acid) can cause Henoch-Schönlein Purpura (HSP), though this is a rare drug-induced adverse reaction.
Evidence for Drug-Induced HSP
Drug-related HSP is a recognized clinical entity, though uncommon. A documented case report describes HSP occurring in a patient treated with cefuroxime (a related beta-lactam antibiotic) and diclofenac, presenting with important systemic manifestations including glomerulonephritis with IgA mesangial deposits 1. While this specific case implicated cefuroxime rather than co-amoxiclav, the patient had a history of purpuric rash after taking cephradine (another cephalosporin) ten years prior, establishing a pattern of beta-lactam-associated vasculitis 1.
The mechanism involves immune complex-mediated leukocytoclastic vasculitis, which can be triggered by various medications including antibiotics 2. Beta-lactam antibiotics as a class have been implicated in drug-induced vasculitic reactions, making co-amoxiclav a plausible trigger 1.
Clinical Recognition and Diagnosis
HSP presents with a characteristic tetrad: palpable purpura (without thrombocytopenia), abdominal pain, arthritis, and renal involvement 2. Key diagnostic features include:
- All patients develop purpuric rash (100%) 2
- Arthritis occurs in 75% of cases 2
- Abdominal pain develops in 60-65% of patients 2
- Renal disease manifests in 40-50% of cases 2
Most patients have an antecedent upper respiratory illness, which may confound the clinical picture when antibiotics like co-amoxiclav are prescribed for respiratory infections 2. This temporal relationship makes distinguishing drug-induced HSP from infection-triggered HSP challenging in clinical practice.
Critical Diagnostic Pitfall
The major clinical challenge is that HSP often follows upper respiratory infections—the exact indication for which co-amoxiclav is commonly prescribed 2. This creates diagnostic ambiguity: is the HSP triggered by the infection itself or by the antibiotic treatment? In the documented case of beta-lactam-associated HSP, the patient had a prior episode with a different cephalosporin, suggesting drug causation rather than coincidental infection-related HSP 1.
Management Approach When HSP Develops
Immediately discontinue co-amoxiclav if HSP is suspected 1. The management priorities are:
- Supportive treatment is the primary intervention, as HSP spontaneously resolves in 94% of children and 89% of adults 2
- Oral prednisone 1-2 mg/kg daily for two weeks can be used for abdominal and joint symptoms 2
- Corticosteroid use in children reduces mean time to resolution of abdominal pain and decreases odds of developing persistent renal disease 2
- Early aggressive therapy with high-dose steroids plus immunosuppressants is recommended for severe renal involvement 2
Long-Term Prognosis and Monitoring
Long-term prognosis depends entirely on the severity of renal involvement 2. End-stage renal disease occurs in 1-5% of patients with HSP 2. Therefore, any patient who develops HSP while taking co-amoxiclav requires:
- Urinalysis for hematuria and proteinuria monitoring
- Blood pressure monitoring
- Renal function assessment
- Long-term nephrology follow-up if renal involvement is present 2
Documentation for Future Prescribing
Document the reaction as a potential drug allergy to beta-lactam antibiotics 1. While skin testing with beta-lactams may be negative (as occurred in the reported case), the clinical history of purpuric vasculitis following beta-lactam exposure should guide future antibiotic selection 1. Avoid all beta-lactam antibiotics (penicillins and cephalosporins) in patients with documented HSP following co-amoxiclav exposure 1.