What the FDA labels say about taking them together
Amiodarone and levothyroxine
Levothyroxine's FDA label of February 20, 2024 names amiodarone in its drug interactions section; the amiodarone labels PlainMeds reads (2) do not name levothyroxine. The levothyroxine label: “Other: Amiodarone); Amiodarone inhibits peripheral conversion of levothyroxine (T4) to triiodothyronine (T3) and may cause isolated biochemical changes in clinically euthyroid patients.”
Check it at the source: the amiodarone FDA label on DailyMed (effective December 9, 2025, Chartwell RX, LLC); the levothyroxine FDA label on DailyMed (effective February 20, 2024, AbbVie Inc.).
What does the amiodarone label say about levothyroxine?
Amiodarone's label (effective December 9, 2025) and its 1 other brand-application label do not name levothyroxine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Amiodarone Hydrochloride), Chartwell RX, LLC, effective December 9, 2025 (SPL set 5520f11d-968d-4f4f-bf57-d14369c0d746), via openFDA; the full label on DailyMed
What does the levothyroxine label say about amiodarone?
Levothyroxine label, drug interactionsOther 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.
Levothyroxine Sodium label (Amneal Pharmaceuticals NY LLC, December 6, 2024), drug interactionsDrug or Drug Class: Aminoglutethimide Amiodarone Iodide (including iodine-containing Radiographic contrast agents) Lithium Methimazole Propylthioracil (PTU) Sulfonamides Tolbutamide; Effect: Long-term lithium therapy can result in goiter in up to 50% of patients, and either subclinical or overt hypothyroidism, each in up to 20% of patients. The fetus, neonate, elderly and euthyroid patients with underlying thyroid disease (e.g., Hashimoto's thyroiditis or with Grave's disease previously treated with radioiodine or surgery) are among those individuals who are particularly susceptible to iodine-induced hypothyroidism. …
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 (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
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
| Amiodarone | Levothyroxine | |
|---|---|---|
| Labeled for | n/a | Hypothyroidism |
| Boxed warning | Yes | Yes |
| Pharmacy cost (NADAC) | $0.122 per tablet 200 mg tablet | $0.0588 per tablet 112 mcg tablet |
| 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