Phenobarbital and Clarithromycin Interaction
Drug interaction information between Phenobarbital and Clarithromycin.
Phenobarbital and Clarithromycin have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Phenobarbital and Clarithromycin. 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
Clarithromycin affects the enzyme system that processes phenobarbital, which can change how much of the drug stays in your body.
FDA Label Information
Other Drugs Metabolized by CYP3A: Alfentanil Bromocriptine Cilostazol Methylprednisolone Vinblastine Phenobarbital St. John’s Wort Use With Caution There have been spontaneous or published reports of CYP3A based interactions of clarithromycin with alfentanil, methylprednisolone, cilostazol, bromocriptine, vinblastine, phenobarbital, and St.
Phenobarbital Also Interacts With
- Nirmatrelvir/Ritonavir major
- Ranolazine major
- Voriconazole major
- Canagliflozin moderate
- Cenobamate moderate
Clarithromycin Also Interacts With
- Quetiapine major
- Pioglitazone major
- Fluconazole major
- Cyclosporine major
- Lurasidone major
Frequently Asked Questions
What SPL severity band is on file for Phenobarbital + Clarithromycin?
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?
Clarithromycin has 81 labeled pairs on file vs Phenobarbital's 59. In the moderate band specifically: Phenobarbital has 13 (also Canagliflozin, Cenobamate, Dapsone Topical, Dolutegravir/Lamivudine); Clarithromycin has 35 (also Omeprazole, Methylprednisolone, Sildenafil, Valproate).
What mechanism field is on file for Phenobarbital and Clarithromycin?
Clarithromycin affects the enzyme system that processes phenobarbital, which can change how much of the drug stays in your body.
Clarithromycin carries more major-labeled pairs than Phenobarbital
SPL source-record counts only. This page's band is moderate · classes on file: Phenobarbital (Anticonvulsant (Barbiturate)); Clarithromycin (Macrolide Antibiotic).
Clarithromycin has 16 major-labeled pairs vs Phenobarbital's 3. This page itself is in the moderate band, not the major band.
3 major · 13 moderate · 43 minor · 59 total
- Other moderate peers for Phenobarbital
- Canagliflozin
- Cenobamate
- Dapsone Topical
- Dolutegravir/Lamivudine
16 major · 35 moderate · 30 minor · 81 total
- Other moderate peers for Clarithromycin
- Omeprazole
- Methylprednisolone
- Sildenafil
- Valproate
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.