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 Aluminum Phosphate Reduced efficacy of levothyroxine Details Levothyroxine Amiodarone Nexterone Decreased levothyroxine efficacy Details Levothyroxine Bugleweed Reduced effectiveness of thyroid hormones Details Levothyroxine Calcium Acetate Calphron Decreased levothyroxine absorption Details Levothyroxine Calcium Citrate Decreased levothyroxine absorption Details Levothyroxine Calcium Silicate Reduced efficacy of levothyroxine Details Levothyroxine Carbamazepine Carbatrol Reduced total and free T4 levels Details Levothyroxine Ceritinib Zykadia Increased risk of hypothyroidism Details Levothyroxine Chlorotrianisene Reduced serum-free thyroxine exposure Details Levothyroxine Chlorpropamide Diabinese® Worsening of glycemic control Details Levothyroxine Cholestyramine Prevalite Reduced efficacy of levothyroxine and an increased risk of hypothyroidism Details Levothyroxine Chromium Decreased levothyroxine absorption Details Levothyroxine Ciprofloxacin Decreased efficacy of levothyroxine Details Levothyroxine Clofibrate Decreased levothyroxine exposure Details Levothyroxine Conjugated / Estrogens Premarin Reduced serum-free thyroxine exposure Details Levothyroxine Conjugated Estrogens Synthetic A Reduced serum-free thyroxine exposure Details Levothyroxine Conjugated Estrogens Synthetic B Reduced serum-free thyroxine exposure Details Levothyroxine Crizotinib Xalkori Increased risk of hypothyroidism Details Levothyroxine Dienestrol Reduced serum-free thyroxine exposure Details Levothyroxine Diethylstilbestrol Reduced serum-free thyroxine exposure Details Levothyroxine Dihydroxyaluminum Aminoacetate Reduced efficacy of levothyroxine Details Levothyroxine Dihydroxyaluminum Sodium Carbonate Reduced efficacy of levothyroxine Details Levothyroxine Dulaglutide Trulicity Worsening of glycemic control Details Levothyroxine Ensartinib Increased risk of hypothyroidism Details Levothyroxine Esterified Estrogens Menest Reduced serum-free thyroxine exposure Details Levothyroxine Estriol Reduced serum-free thyroxine exposure Details Levothyroxine Estropipate Ogen Reduced serum-free thyroxine exposure Details Levothyroxine Ethinyl Estradiol Reduced serum-free thyroxine exposure Details Levothyroxine Etofenamate Transient increase in FT4 followed by decrease in serum T4 and normal FT4 and TSH levels Details Levothyroxine Exenatide Bydureon Worsening of glycemic control Details Levothyroxine Fosphenytoin Cerebyx Reduced efficacy of levothyroxine Details Levothyroxine Fruquintinib Increased risk of hypothyroidism Details Levothyroxine Glyburide DiaBeta® Worsening of glycemic control Details Levothyroxine Imatinib Gleevec Increased risk of hypothyroidism Details Levothyroxine Insulin Afrezza May decrease blood glucose lowering effect of insulin Details Levothyroxine Insulin Aspart, Recombinant Fiasp Worsening of glycemic control Details Levothyroxine Insulin Bovine Worsening of glycemic control Details Levothyroxine Insulin Degludec Tresiba Worsening of glycemic control Details Levothyroxine Insulin Detemir Levemir Worsening of glycemic control Details Levothyroxine Insulin Glulisine Apidra Worsening of glycemic control 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.