Augmentin and Allopurinol Interaction
Augmentin (amoxicillin-clavulanate) can be co-administered with allopurinol, but the concurrent use increases the incidence of skin rashes compared to amoxicillin alone. 1
Key Interaction: Increased Rash Risk
The FDA drug label explicitly states that concurrent administration of allopurinol and amoxicillin increases the incidence of rashes in patients receiving both drugs compared to patients receiving amoxicillin alone. 1 It remains unclear whether this potentiation of rashes is due to allopurinol itself or the underlying hyperuricemia present in these patients. 1
Clinical Management Approach
No dose adjustments are required for either medication when used together. 1 The interaction is primarily dermatologic rather than pharmacokinetic:
- Monitor closely for skin reactions during the first few days of concurrent therapy 1
- Counsel patients to report any rash, itching, or skin changes immediately 1
- Consider the clinical necessity of using both agents simultaneously, particularly if alternative antibiotics are available 1
Important Distinction from Azathioprine
The allopurinol interaction with Augmentin differs fundamentally from its interaction with thiopurine drugs (azathioprine, 6-mercaptopurine):
- With thiopurines: Allopurinol requires a 65-75% dose reduction of the chemotherapeutic agent due to severe myelotoxicity risk 2, 3, 4
- With Augmentin: No dose adjustment is needed; only increased rash surveillance is required 1
Risk Stratification
Patients at higher baseline risk for allopurinol hypersensitivity reactions (Han-Chinese, Korean, Thai populations with HLA-B*58:01) may warrant extra caution when adding Augmentin, though this specific combination has not been studied in these populations. 2
Common Pitfall to Avoid
Do not confuse this interaction with the allopurinol-azathioprine interaction. The latter requires dramatic dose reduction and close hematologic monitoring 5, while the Augmentin-allopurinol combination simply requires dermatologic vigilance without dose modification. 1