Phenobarbital and Griseofulvin Interaction
Drug interaction information between Phenobarbital and Griseofulvin.
Phenobarbital and Griseofulvin have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Phenobarbital and Griseofulvin. 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
Phenobarbital stops your body from fully absorbing griseofulvin into your bloodstream. This leads to lower levels of the medicine in your system.
FDA Label Information
Griseofulvin Phenobarbital appears to interfere with the absorption of orally administered griseofulvin, thus decreasing its blood level. The effect of the resultant decreased blood levels of griseofulvin on therapeutic response has not been established.
Phenobarbital Also Interacts With
- Nirmatrelvir/Ritonavir major
- Ranolazine major
- Voriconazole major
- Canagliflozin moderate
- Cenobamate moderate
Griseofulvin Also Interacts With
- Warfarin minor
- Cyclosporine minor
- Drospirenone/Ethinyl Estradiol minor
- Estradiol minor
- Ethinyl Estradiol/Etonogestrel minor
Frequently Asked Questions
What SPL severity band is on file for Phenobarbital + Griseofulvin?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Phenobarbital has 59 labeled pairs on file vs Griseofulvin's 12. In the minor band specifically: Phenobarbital has 43 (also Estradiol, Doxycycline, Progesterone, Bazedoxifene); Griseofulvin has 12 (also Warfarin, Cyclosporine, Drospirenone, Estradiol).
What mechanism field is on file for Phenobarbital and Griseofulvin?
Phenobarbital stops your body from fully absorbing griseofulvin into your bloodstream. This leads to lower levels of the medicine in your system.
Phenobarbital carries more major-labeled pairs than Griseofulvin
SPL source-record counts only. This page's band is minor · classes on file: Phenobarbital (Anticonvulsant (Barbiturate)); Griseofulvin (Antifungal).
Phenobarbital has 3 major-labeled pairs vs Griseofulvin's 0. This page itself is in the minor band, not the major band.
3 major · 13 moderate · 43 minor · 59 total
- Other minor peers for Phenobarbital
- Estradiol
- Doxycycline
- Progesterone
- Bazedoxifene
0 major · 0 moderate · 12 minor · 12 total
- Other minor peers for Griseofulvin
- Warfarin
- Cyclosporine
- Drospirenone
- Estradiol
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.