What the FDA labels say about taking them together
Ketamine and levothyroxine
Levothyroxine's FDA label of February 20, 2024 names ketamine in its drug interactions section; the ketamine label PlainMeds reads does not name levothyroxine.
Check it at the source: the ketamine FDA label on DailyMed (effective March 27, 2026, Par Health USA, LLC); the levothyroxine FDA label on DailyMed (effective February 20, 2024, AbbVie Inc.).
What does the ketamine label say about levothyroxine?
Ketamine's label (effective March 27, 2026) does 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 (Ketalar), Par Health USA, LLC, effective March 27, 2026 (SPL set 14e8f864-8b8a-4e7e-8439-e510d3107063), via openFDA; the full label on DailyMed
What does the levothyroxine label say about ketamine?
Levothyroxine label, drug interactionsConcurrent use of ketamine and SYNTHROID may produce marked hypertension and tachycardia.
Levothyroxine Sodium label (Amneal Pharmaceuticals NY LLC, December 6, 2024), drug interactionsKetamine Concurrent use may produce marked hypertension and tachycardia; cautious administration to patients receiving thyroid hormone therapy is recommended.
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
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
| Ketamine | Levothyroxine | |
|---|---|---|
| Labeled for | n/a | Hypothyroidism |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.556 per mL 500 mg/10 mL vial | $0.0588 per tablet 112 mcg tablet |
| Shortage now | A presentation being discontinued | 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