Liothyronine and Levothyroxine Interaction
Drug interaction information between Liothyronine and Levothyroxine.
Liothyronine and Levothyroxine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Liothyronine and Levothyroxine. 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
This interaction can stop your body from turning one type of thyroid hormone into another, which can change your blood test results.
FDA Label Information
Other drugs: Amiodarone Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes (increase in serum free-T4, and decreased or normal free-T3) in clinically euthyroid patients.
Liothyronine Also Interacts With
- Sertraline minor
- Furosemide minor
- Propranolol minor
- Amitriptyline minor
- Carbamazepine minor
Levothyroxine Also Interacts With
- Sertraline minor
- Furosemide minor
- Propranolol minor
- Ferrous Sulfate minor
- Amitriptyline minor
Frequently Asked Questions
What SPL severity band is on file for Liothyronine + Levothyroxine?
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?
Levothyroxine has 22 labeled pairs on file vs Liothyronine's 17. In the minor band specifically: Liothyronine has 17 (also Sertraline, Furosemide, Propranolol, Amitriptyline); Levothyroxine has 22 (also Sertraline, Furosemide, Propranolol, Ferrous Sulfate).
What mechanism field is on file for Liothyronine and Levothyroxine?
This interaction can stop your body from turning one type of thyroid hormone into another, which can change your blood test results.
Levothyroxine's labeled portfolio outnumbers Liothyronine
SPL source-record counts only. This page's band is minor · classes on file: Liothyronine (Thyroid Hormone (T3)); Levothyroxine (Thyroid Hormone).
0 major · 0 moderate · 17 minor · 17 total
- Other minor peers for Liothyronine
- Sertraline
- Furosemide
- Propranolol
- Amitriptyline
0 major · 0 moderate · 22 minor · 22 total
- Other minor peers for Levothyroxine
- Sertraline
- Furosemide
- Propranolol
- Ferrous Sulfate
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.