Allopurinol and Amoxicillin/Clavulanate Interaction
Drug interaction information between Allopurinol and Amoxicillin/Clavulanate.
Allopurinol and Amoxicillin/Clavulanate have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Allopurinol and Amoxicillin/Clavulanate. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Taking these two drugs together increases the chance of developing a skin rash. It is not fully known if the rash is caused by the drugs themselves or the medical condition being treated.
FDA Label Information
( 7.1 ) Concomitant use of AUGMENTIN and oral anticoagulants may increase the prolongation of prothrombin time.( 7.2 ) Co-administration with allopurinol increases the risk of rash. 7.3 Allopurinol The concurrent administration of allopurinol and amoxicillin increases the incidence of rashes in patients receiving both drugs as compared to patients receiving amoxicillin alone. It is not known whether this potentiation of amoxicillin rashes is due to allopurinol or the hyperuricemia present in these patients.
Allopurinol Also Interacts With
- Pegloticase major
- Cyclosporine moderate
- Amoxicillin moderate
- Warfarin minor
- Theophylline minor
Amoxicillin/Clavulanate Also Interacts With
- Probenecid moderate
- Amoxicillin minor
- Estradiol minor
- Progesterone minor
Frequently Asked Questions
What SPL severity band is on file for Allopurinol + Amoxicillin/Clavulanate?
Compiled FDA labeling labels this pair moderate. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Allopurinol has 10 labeled pairs on file vs Amoxicillin/Clavulanate's 5. In the moderate band specifically: Allopurinol has 3 (also Cyclosporine, Amoxicillin); Amoxicillin/Clavulanate has 2 (also Probenecid).
What mechanism field is on file for Allopurinol and Amoxicillin/Clavulanate?
Taking these two drugs together increases the chance of developing a skin rash. It is not fully known if the rash is caused by the drugs themselves or the medical condition being treated.
Allopurinol carries more major-labeled pairs than Amoxicillin/Clavulanate
SPL source-record counts only. This page's band is moderate · classes on file: Allopurinol (Xanthine Oxidase Inhibitor); Amoxicillin/Clavulanate (Penicillin / Beta-Lactamase Inhibitor Combination).
Allopurinol has 1 major-labeled pair vs Amoxicillin/Clavulanate's 0. This page itself is in the moderate band, not the major band.
1 major · 3 moderate · 6 minor · 10 total
- Other moderate peers for Allopurinol
- Cyclosporine
- Amoxicillin
0 major · 2 moderate · 3 minor · 5 total
- Other moderate peers for Amoxicillin/Clavulanate
- Probenecid
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.