Cephalexin and Metformin Interaction
Drug interaction information between Cephalexin and Metformin.
Cephalexin and Metformin have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Cephalexin and Metformin. 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
Cephalexin makes it harder for your kidneys to remove metformin from your body. This causes the metformin to stay in your blood longer and reach higher levels than usual.
FDA Label Information
7 DRUG INTERACTIONS Metformin: increased metformin concentrations. ( 7.3 ) 7.1 Metformin Administration of cephalexin with metformin results in increased plasma metformin concentrations and decreased renal clearance of metformin. Careful patient monitoring and dose adjustment of metformin is recommended in patients concomitantly taking cephalexin and metformin [see Clinical Pharmacology (12.3) ].
Metformin Also Interacts With
- Bictegravir/Emtricitabine/Tenofovir moderate
- Dolutegravir/Lamivudine moderate
- Empagliflozin moderate
- Empagliflozin/Linagliptin moderate
- Ertugliflozin moderate
Frequently Asked Questions
What SPL severity band is on file for Cephalexin + Metformin?
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?
Metformin has 27 labeled pairs on file vs Cephalexin's 2. In the minor band specifically: Cephalexin has 1; Metformin has 17 (also Topiramate, Dolutegravir, Ranolazine, Cimetidine).
What mechanism field is on file for Cephalexin and Metformin?
Cephalexin makes it harder for your kidneys to remove metformin from your body. This causes the metformin to stay in your blood longer and reach higher levels than usual.
Metformin's labeled portfolio outnumbers Cephalexin
SPL source-record counts only. This page's band is minor · classes on file: Cephalexin (First-Generation Cephalosporin); Metformin (Biguanide).
0 major · 1 moderate · 1 minor · 2 total
Cephalexin has no other minor-band peer in this dataset besides Metformin.
0 major · 10 moderate · 17 minor · 27 total
- Other minor peers for Metformin
- Topiramate
- Dolutegravir
- Ranolazine
- Cimetidine
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.