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Generic name: levothyroxine sodium

What is Tirosint?

Tirosint is a prescription medicine that contains a hormone called levothyroxine which is normally produced by the thyroid gland. Tirosint is used to treat adults and children 6 years of age or older:

  • to replace or give extra levothyroxine in people whose thyroid does not produce enough of this hormone.
  • who need surgery and radioiodine therapy to manage a type of thyroid cancer called thyroid-dependent well-differentiated thyroid cancer.

Tirosint should not be used to treat people who are recovering from swelling of the thyroid gland (thyroiditis) and whose bodies do not produce enough levothyroxine for a short time.

Tirosint is unsuitable for children less than 6 years of age or who may be unable to swallow an intact capsule.

What is the most important information I should know about Tirosint?

  • Do not use Tirosint to treat weight problems or weight loss.
  • Do not take more Tirosint than your doctor prescribes for you to take. Over dosage or taking too much Tirosint may cause life-threatening side effects or death.

Who should not take Tirosint?

Do not take Tirosint:

  • if your adrenal glands are not working well and you have not been treated for this problem.

What should I tell my healthcare provider before taking Tirosint?

Before you take Tirosint, tell your doctor about all of your medical conditions, including if you:

  • have or had heart problems.
  • have or had thyroid nodules.
  • have kidney or pituitary gland problems.
  • have any food or drug allergies.
  • have a low red blood cell count (anemia).
  • have diabetes.
  • have weak bones (osteoporosis).
  • have or had a history of blood clotting problems.
  • have recently received radiation therapy with iodine (such as I-131).
  • are pregnant or plan to become pregnant. Tirosint may harm your unborn baby. Your doctor may need to change your Tirosint dose while you are pregnant.
  • are breastfeeding. Tirosint can pass into your milk. Talk to your doctor about the best way to feed your baby if you take Tirosint.

Tell your doctor about all the medicines you take including prescription and over-the-counter medicines, vitamins, and herbal supplements. Tirosint may affect the way other medicines work, and other medicines may affect how Tirosint works. You can ask your doctor or pharmacist for a list of medicines that interact with Tirosint.

How should I take Tirosint?

  • Take Tirosint exactly as your doctor tells you to take it.
  • Your doctor will tell you how much Tirosint to take each day.
  • Swallow Tirosint capsules whole. Do not cut, crush, or chew Tirosint capsules before swallowing. If you or your child cannot swallow Tirosint capsules whole, tell your doctor. You may need a different medicine.
  • Your doctor may change your dose, if needed.
  • Take your dose of Tirosint 1 time each day, 30 minutes to 1 hour before breakfast, on an empty stomach.
  • Certain medicines can interfere with how Tirosint is absorbed by your body. Take Tirosint:
    • at least 4 hours before or after you take medicines that contain calcium carbonate or iron (ferrous sulfate).
    • at least 4 hours before you take medicines that contain bile acid sequestrants or ion exchange resins.
  • Know the medicines that you take. Ask your doctor or pharmacist for a list of these medicines, if you are not sure.
  • Certain foods including soybean flour, cotton seed meal, walnuts, and dietary fiber can affect your treatment and dose of Tirosint. Talk to your doctor if you eat or drink these foods.
  • Do not remove Tirosint capsules from the original blister package until you are ready to take them.
  • Your doctor should do certain blood tests while you are taking Tirosint and may change your daily dose of Tirosint as needed. You should not stop taking Tirosint or change your dose unless your doctor tells you to.
  • It may take weeks before you notice your symptoms getting better. Keep using this medicine even if you feel well.
  • If you take too much Tirosint or overdose, call your doctor or poison control center at 1-800-222-1222, or go to the nearest hospital emergency room right away.

What are the possible side effects of Tirosint?

Tirosint may cause serious side effects, including:

  • heart problems. You may experience an increased heart rate, chest pain and irregular heartbeat. Your risk of developing heart problems may be greater if you are elderly, have heart problems, or if you take too much Tirosint. Your doctor may reduce your dose or stop treatment with Tirosint for a while if you develop heart problems.
  • worsening diabetic control. If you are diabetic, it may be harder to control your blood sugar levels causing hyperglycemia while taking Tirosint. Check your blood sugar levels closely after starting, changing, or stopping treatment with Tirosint. Your doctor may have to change your diabetes treatment plan.
  • weak or brittle bones. Your risk of developing weak or brittle bones may be greater if you are post-menopausal or you take too much Tirosint.

The most common side effects of Tirosint include:

  • irregular heartbeat
  • chest pain
  • shortness of breath
  • leg cramps
  • headache
  • nervousness
  • hives or skin rash
  • irritability
  • sleep problems (insomnia)
  • tremors
  • muscle weakness
  • change in appetite
  • weight loss
  • vomiting
  • diarrhea
  • sweating a lot
  • heat intolerance
  • fever
  • changes in menstrual period

Other side effects may include:

  • partial hair loss during the first months of treatment with Tirosint. This usually lasts a short period of time (temporary).

These are not all the possible side effects of Tirosint. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

You may also report side effects to IBSA Pharma Inc. at 1-800-587-3513 or

Tirosint Images

General information about the safe and effective use of Tirosint

Medicines are sometimes prescribed for purposes other than those listed in a Patient Information leaflet. Do not use Tirosint for a condition for which it was not prescribed. Do not give Tirosint to other people, even if they have the same symptoms that you have. It may harm them. You can ask your pharmacist or doctor for information about Tirosint that is written for health professionals.

How should I store Tirosint?

  • Store Tirosint at room temperature between 68°F to 77°F (20°C to 25°C).
  • Store Tirosint away from heat, light, and moisture.
  • Keep Tirosint in the original blister pack until you are ready to use it.

Keep Tirosint and all medicines out of the reach of children.

What are the ingredients in Tirosint?

Active ingredient: levothyroxine sodium

Inactive ingredients: gelatin, glycerin, and water

Source: National Library of Medicine. Last updated April 17, 2019.