Tetracycline and Doxycycline Hyclate Interaction
Drug interaction information between Tetracycline and Doxycycline Hyclate.
Tetracycline and Doxycycline Hyclate have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Tetracycline and Doxycycline Hyclate. 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
These drugs are very similar and work in the same way, so taking them together can lead to too much medicine in your system and more side effects.
FDA Label Information
Drug Interactions Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage. Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines in conjunction with penicillin. Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations.
Tetracycline Also Interacts With
- Theophylline major
- Doxycycline moderate
- Minocycline moderate
- Zinc Sulfate minor
- Atovaquone/Proguanil minor
Doxycycline Hyclate Also Interacts With
- Doxycycline minor
- Carbamazepine minor
- Bismuth Subsalicylate minor
- Phenytoin minor
Frequently Asked Questions
What SPL severity band is on file for Tetracycline + Doxycycline Hyclate?
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?
Tetracycline has 12 labeled pairs on file vs Doxycycline Hyclate's 5. In the moderate band specifically: Tetracycline has 3 (also Doxycycline, Minocycline); Doxycycline Hyclate has 1.
What mechanism field is on file for Tetracycline and Doxycycline Hyclate?
These drugs are very similar and work in the same way, so taking them together can lead to too much medicine in your system and more side effects.
Tetracycline carries more major-labeled pairs than Doxycycline Hyclate
SPL source-record counts only. This page's band is moderate · classes on file: Tetracycline (Tetracycline Antibiotic); Doxycycline Hyclate (Tetracycline Antibiotic (Antimalarial)).
Tetracycline has 1 major-labeled pair vs Doxycycline Hyclate's 0. This page itself is in the moderate band, not the major band.
1 major · 3 moderate · 8 minor · 12 total
- Other moderate peers for Tetracycline
- Doxycycline
- Minocycline
0 major · 1 moderate · 4 minor · 5 total
Doxycycline Hyclate has no other moderate-band peer in this dataset besides Tetracycline.
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.