Levothyroxine

214 interactions 1 explained in plain English 219 cited references
Also sold as: Ermeza Euthyrox Levo-T Levo-T® Levothroid® Levoxyl Levoxyl® Synthroid Synthroid® Thyquidity Thyro-Tabs Thyrocryn ThyroKare Tirosint Tirosint® Unithroid Unithroid®
About Levothyroxine

Levothyroxine is a hormone used to replace thyroid hormone and treat hypothyroidism and thyroid cancer. Read the full Levothyroxine drug information page →

Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated Aug 10, 2026 · Editorial policy · Data sources

Sources: FDA prescribing information (Structured Product Labeling), the published literature cited in each entry, DDInter 2.0 (a major open-access drug-interaction database), and legacy DrugBank interaction data distributed by the NIH's RxNav service (decommissioned in 2024) — analyzed and reviewed by our pharmacist team. How we build this library →

Most serious with: Insulin Icodec-Abae Polystyrene Sulfonate Iomeprol Insulin Glargine, Recombinant Furosemide Epinephrine
17 Major 196 Moderate 1 Minor
All (214) Major (17) Moderate (196) Minor (1)

Moderate

Levothyroxine Polyestradiol Phosphate Reduced serum-free thyroxine exposure Details Levothyroxine Ponatinib Iclusig Increased risk of hypothyroidism Details Levothyroxine Pralsetinib Gavreto Increased risk of hypothyroidism Details Levothyroxine Pramlintide Symlin Worsening of glycemic control Details Levothyroxine Primidone Mysoline Reduced levothyroxine exposure and reduced efficacy of levothyroxine Details Levothyroxine Promestriene Reduced serum-free thyroxine exposure Details Levothyroxine Quinestrol Reduced serum-free thyroxine exposure Details Levothyroxine Quizartinib Vanflyta Increased risk of hypothyroidism Details Levothyroxine Rabeprazole Aciphex Reduced efficacy of levothyroxine and an increased risk of hypothyroidism Details Levothyroxine Raloxifene Evista Decreased levothyroxine efficacy Details Levothyroxine Regorafenib Stivarga Increased risk of hypothyroidism Details Levothyroxine Remibrutinib Rhapsido Increased risk of hypothyroidism Details Levothyroxine Repaglinide Prandin® Worsening of glycemic control Details Levothyroxine Repotrectinib Augtyro Increased risk of hypothyroidism Details Levothyroxine Rifampin Rifadin Reduced efficacy of levothyroxine Details Levothyroxine Rilzabrutinib Wayrilz Increased risk of hypothyroidism Details Levothyroxine Ripretinib Qinlock Increased risk of hypothyroidism Details Levothyroxine Ritlecitinib Litfulo Increased risk of hypothyroidism Details Levothyroxine Ritonavir Norvir Loss of levothyroxine efficacy Details Levothyroxine Rivaroxaban Xarelto Increased response to oral anticoagulant therapy Details Levothyroxine Rosiglitazone Avandia® Worsening of glycemic control Details Levothyroxine Ruxolitinib Jakafi Increased risk of hypothyroidism Details Levothyroxine Saxagliptin Onglyza Worsening of glycemic control Details Levothyroxine Selpercatinib Retevmo Increased risk of hypothyroidism Details Levothyroxine Semaglutide Ozempic Increased levothyroxine exposure, decreased TSH and worsening of glycemic control Details Levothyroxine Sevabertinib Hyrnuo Increased risk of hypothyroidism Details Levothyroxine Sevelamer RenaGel Reduced efficacy of levothyroxine and an increased risk of hypothyroidism Details Levothyroxine Simethicone Alka-Seltzer® Anti-Gas Decreased levothyroxine efficacy Details Levothyroxine Sitagliptin Brynovin Worsening of glycemic control Details Levothyroxine Sodium Bicarbonate Alka-Seltzer® Heartburn Reduced efficacy of levothyroxine Details Levothyroxine Sorafenib Nexavar Increased risk of hypothyroidism Details Levothyroxine Sucralfate Carafate Reduced efficacy of levothyroxine Details Levothyroxine Sucroferric Oxyhydroxide Altered absorption of oral levothyroxine Details Levothyroxine Sunitinib Sutent Increased risk of hypothyroidism Details Levothyroxine Taletrectinib Ibtrozi Increased risk of hypothyroidism Details Levothyroxine Tamoxifen Nolvadex® Decreased levothyroxine exposure Details Levothyroxine Tepotinib Tepmetko Increased risk of hypothyroidism Details Levothyroxine Testosterone Androderm Increased levothyroxine exposure Details Levothyroxine Tibolone Reduced serum-free thyroxine exposure Details Levothyroxine Tirzepatide Mounjaro Increased levothyroxine exposure and decreased TSH Details

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Educational information only, not medical advice. Always confirm interactions with your pharmacist or prescriber before making any change to your medications.