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Levothyroxine (By injection)

Levothyroxine (lee-voe-thye-ROX-een)

Treats severe hypothyroidism.

Brand Name(s):

PremierPro Rx Levothyroxine Sodium, levothyroxine sodium Novaplus

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. You should not receive it if you had an allergic reaction to levothyroxine, or if you have an uncorrected adrenal gland problem.

How to Use This Medicine:


  • Your doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given through a needle placed in your vein or muscle.
  • You will receive a few doses of this medicine, then your doctor may switch you to an oral dosage form.
  • A nurse or other health provider will give you this medicine.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Some medicines can affect how levothyroxine works. Tell your doctor if you are using any of the following:
    • Amiodarone, asparaginase, aspirin, clofibrate, digitalis, fluorouracil, heroin, ketamine, methadone, mitotane, nicotinic acid, rifampin, tamoxifen
    • Beta blocker (including propranolol)
    • Birth control pills containing estrogen
    • Blood thinner (including heparin, warfarin)
    • Diuretic (water pill, including furosemide)
    • Insulin or oral diabetes medicine
    • Medicine to treat depression (including amitriptyline, maprotiline, sertraline)
    • Medicine to treat seizures (including carbamazepine, phenobarbital, phenytoin)
    • NSAID pain or arthritis medicine
    • Steroid medicine (including dexamethasone)

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have heart or blood vessel disease, diabetes, or pernicious anemia.
  • This medicine may cause the following problems:
    • Increased risk of heart rhythm problems, heart attack
    • New or worsening heart failure
    • Adrenal gland problems
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
  • Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Fast, pounding, or uneven heartbeat
  • Chest pain that may spread, trouble breathing, nausea, unusual sweating, fainting
  • Nervousness, confusion, loss of consciousness, sudden weakness, darkening of the skin, fever, chills

If you notice these less serious side effects, talk with your doctor:

  • Appetite changes, weight loss
  • Difficulty sleeping
  • Sweating, intolerance to heat
  • Tremors

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

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