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 →

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 Insulin Lispro, Recombinant Admelog May decrease blood glucose lowering effect of insulin lispro Details Levothyroxine Kelp Increased risk of hypo- or hyperthyroidism, altered thyroid hormone dosage requirements, and inaccurate thyroid function tests use... Details Levothyroxine Lanthanum Carbonate Fosrenol Reduced levothyroxine exposure and serum thyroxine (T4) level, reduced efficacy of levothyroxine and an increased risk of hypothyr... Details Levothyroxine Lapatinib Tykerb Increased risk of hypothyroidism Details Levothyroxine Larotrectinib Increased risk of hypothyroidism Details Levothyroxine Lazertinib Lazcluze Increased risk of hypothyroidism Details Levothyroxine Linagliptin Tradjenta Worsening of glycemic control Details Levothyroxine Liraglutide Saxenda Worsening of glycemic control Details Levothyroxine Lithospermum Reduced effectiveness of thyroid hormones Details Levothyroxine Lixisenatide Worsening of glycemic control Details Levothyroxine Lopinavir Loss of levothyroxine efficacy Details Levothyroxine Lorlatinib Lorbrena Increased risk of hypothyroidism Details Levothyroxine Magaldrate Reduced efficacy of levothyroxine Details Levothyroxine Magnesium Carbonate Reduced efficacy of levothyroxine Details Levothyroxine Magnesium Hydroxide Almacone® (containing Aluminum Hydroxide, Magnesium Hydroxide, Simethicone) Reduced efficacy of levothyroxine Details Levothyroxine Magnesium Oxide Mag-Ox 400 Reduced efficacy of levothyroxine Details Levothyroxine Magnesium Peroxide Reduced efficacy of levothyroxine Details Levothyroxine Magnesium Trisilicate Reduced efficacy of levothyroxine Details Levothyroxine Meclofenamate Meclodium® Transient increase in FT4 followed by decrease in serum T4 and normal FT4 and TSH levels Details Levothyroxine Mestranol Reduced serum-free thyroxine exposure Details Levothyroxine Metformin Fortamet® An increased risk of hyperglycemia and potential loss of glycemic control Details Levothyroxine Methyltestosterone Increased levothyroxine exposure Details Levothyroxine Mifepristone Korlym Decreased levothyroxine efficacy Details Levothyroxine Miglitol Glyset® Worsening of glycemic control Details Levothyroxine Momelotinib Ojjaara Increased risk of hypothyroidism Details Levothyroxine Nateglinide Starlix® Worsening of glycemic control Details Levothyroxine Neratinib Nerlynx Increased risk of hypothyroidism Details Levothyroxine Nilotinib Increased risk of hypothyroidism Details Levothyroxine Nintedanib Ofev Increased risk of hypothyroidism Details Levothyroxine Osimertinib Tagrisso Increased risk of hypothyroidism Details Levothyroxine Pacritinib Vonjo® Increased risk of hypothyroidism Details Levothyroxine Pantoprazole Protonix Reduced efficacy of levothyroxine and an increased risk of hypothyroidism Details Levothyroxine Patiromer Veltassa Reduced levothyroxine exposure and reduced efficacy of levothyroxine Details Levothyroxine Pazopanib Votrient Increased risk of hypothyroidism Details Levothyroxine Pemigatinib Pemazyre Increased risk of hypothyroidism Details Levothyroxine Pexidartinib Turalio Increased risk of hypothyroidism Details Levothyroxine Phenobarbital Fidoquel Reduced levothyroxine exposure and reduced efficacy of levothyroxine Details Levothyroxine Phenytoin Dilantin Reduced efficacy of levothyroxine Details Levothyroxine Pioglitazone Actos Worsening of glycemic control Details Levothyroxine Pirtobrutinib Jaypirca Increased risk of hypothyroidism 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.