What the FDA labels say about taking them together
Levothyroxine and orlistat
Levothyroxine's FDA label of February 20, 2024 names orlistat in its drug interactions section, and orlistat's label names levothyroxine too. The levothyroxine label: “Orlistat Monitor patients treated concomitantly with orlistat and LEVOXYL for changes in thyroid function.”
Check it at the source: the levothyroxine FDA label on DailyMed (effective February 20, 2024, AbbVie Inc.); the orlistat FDA label on DailyMed (effective March 18, 2026, Haleon US Holdings LLC).
What does the levothyroxine label say about orlistat?
Levothyroxine label, drug interactionsOrlistat Monitor patients treated concomitantly with orlistat and SYNTHROID for changes in thyroid function.
Levothyroxine Sodium label (Amneal Pharmaceuticals NY LLC, December 6, 2024), drug interactionsDrug or Drug Class: Antacids - Aluminum & Magnesium Hydroxides - Simethicone Bile Acid Sequestrants - Cholestyramine - Colestipol Calcium Carbonate Cation Exchange Resins - Kayexalate Ferrous Sulfate Orlistat Sucralfate; Effect: Concurrent use may reduce the efficacy of levothyroxine by binding and delaying or preventing absorption, potentially resulting in hypothyroidism. Calcium carbonate may form an insoluble chelate with levothyroxine, and ferrous sulfate likely forms a ferric-thyroxine complex. Administer levothyroxine at least 4 hours apart from these agents. Patients treated concomitantly with orlistat and levothyroxine should be monitored for changes in thyroid function.
Source: FDA drug label (Levothyroxine Sodium, NDA021210), Amneal Pharmaceuticals NY LLC, effective December 6, 2024 (SPL set fca88c97-5cd4-4834-ba87-deb5bd637788), via openFDA
Source: FDA drug label (Levothyroxine Sodium, NDA021116), Bryant Ranch Prepack, effective July 29, 2025 (SPL set 9e3bffb9-f66e-4c73-befc-e60d769f6610), via openFDA
Source: FDA drug label (Levoxyl, NDA021301), Pfizer Laboratories Div Pfizer Inc, effective December 15, 2020 (SPL set 758588c3-c63e-491b-0aa2-4f50d80cb174), via openFDA
Source: FDA drug label (Synthroid), AbbVie Inc., effective February 20, 2024 (SPL set 1e11ad30-1041-4520-10b0-8f9d30d30fcc), via openFDA; the full label on DailyMed
What does the orlistat label say about levothyroxine?
Orlistat label, drug interactions (prescription label)Patients treated concomitantly with XENICAL and levothyroxine should be monitored for changes in thyroid function.
Orlistat label, warnings and precautions (prescription label)Interactions and Decreased Vitamin Absorption XENICAL may interact with concomitant drugs including cyclosporine, levothyroxine, warfarin, amiodarone, antiepileptic drugs, and antiretroviral drugs [see Drug Interactions (7) ].
Source: FDA drug label (ALLI), Haleon US Holdings LLC, effective March 18, 2026 (SPL set a2d3bd73-f3af-4ea5-a57c-66b0004cfe4f), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Levothyroxine | Orlistat | |
|---|---|---|
| Labeled for | Hypothyroidism | Weight management |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.0588 per tablet 112 mcg tablet | $7.00 per capsule 120 mg capsule |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once