Levothyroxine is a synthetic form of the thyroid hormone thyroxine (T4) that’s used to treat an underactive thyroid, known as hypothyroidism. It’s the most commonly prescribed medication in the United States, with around 123 million prescriptions written in 2016. There’s a great deal of misinformation regarding the safety and effectiveness of generic levothyroxine as compared to brand names like Synthroid. Here’s what you need to know about taking generic levothyroxine to treat your hypothyroidism.
American Thyroid Association. Hypothyroidism: A Booklet for Patients and Their Families. https://www.thyroid.org/wp-content/uploads/patients/brochures/Hypothyroidism_web_booklet.pdf. Accessed March 27, 2019.
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Tirosint [package insert]. Lugano, Switzerand: Institut Biochimique SA (IBSA); 2018.
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Data on file, Institut Biochimique SA (IBSA).
Synthroid [package insert]. North Chicago, IL: AbbVie Inc; 2018.
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Seng Yue S, Benvenga S, Scarsi C, Loprete L, Ducharme MP. When bioequivalence in healthy volunteers may not translate to bioequivalence in patients: differential effects of increased gastric pH on the pharmacokinetics of levothyroxine capsules and tablets. J Pharm Pharm Sci. 2015;18(5):844-855.
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Based on RelayHealth eVoucherRx™ Network pharmacy paid claims from April 2018–March 2019.
TIROSINT® (levothyroxine sodium) capsules, is a prescription medicine that contains a hormone called levothyroxine which is normally produced in your body by the thyroid gland. It is meant to replace the hormone to treat a condition called hypothyroidism. TIROSINT is not for use in people with temporary hypothyroidism caused by thyroiditis, or inflammation of the thyroid gland
Tirosint Important Safety Information
IMPORTANT SAFETY INFORMATION for TIROSINT (levothyroxine sodium) CAPSULES
NOT FOR TREATMENT OF OBESITY OR FOR WEIGHT LOSS
Thyroid hormones, including TIROSINT, either alone or with other therapeutic agents, should not be used for the treatment of obesity or for weight loss.
In euthyroid patients, doses within the range of daily hormonal requirements are ineffective for weight reduction.
Larger doses may produce serious or even life threatening manifestations of toxicity, particularly when given in association with sympathomimetic amines such as those used for their anorectic effects.
What is the most important information you should know about TIROSINT?
TIROSINT® (levothyroxine sodium) is a prescription medicine that contains a hormone called levothyroxine which is normally produced in your body by the thyroid gland. It is used to treat adults and children 6 years of age and older:
To replace or give extra levothyroxine in people whose thyroid gland does not naturally produce enough (a condition called hypothyroidism).
Who need surgery and radioiodine therapy to manage a type of thyroid cancer called thyroid-dependent well-differentiated thyroid cancer.
Do not use TIROSINT to treat weight problems or for weight loss. Do not take more TIROSINT than your doctor prescribes. Over dosage or taking too much TIROSINT may cause life-threatening side effects or death.
TIROSINT should not be used by children less than 6 years of age or who cannot swallow an intact capsule. TIROSINT is also not for use in people with temporary hypothyroidism caused by thyroiditis, or inflammation of the thyroid gland.
Do not take TIROSINT if your adrenal glands are not working well and you have not been treated with glucocorticoid replacement for this problem.
Before you take TIROSINT, tell your healthcare provider about all your medical conditions, including if you: Currently have or have previously had heart problems; currently have or have previously had thyroid nodules; have kidney or pituitary gland problems; have any food or drug allergies; have a low red blood cell count; have diabetes; have weak or weakening bones (osteoporosis); currently have or have previously had a history of blood clotting problems.
Also tell your healthcare provider if you are: Pregnant or planning to become pregnant, or are breastfeeding. TIROSINT may harm your unborn baby. Your doctor may need to change your TIROSINT dose while you are pregnant. TIROSINT passes into breast milk. Talk to your doctor about the best way to feed your baby if you take TIROSINT.
It is important that you 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. Ask your doctor or pharmacist for a list of medicines that may interact with TIROSINT. Certain foods such as soybean flour, cottonseed meal, walnuts, dietary fiber, and grapefruits or grapefruit juice may affect the way that your body absorbs TIROSINT. Tell your healthcare provider if you regularly eat these foods, as they may require your dose of TIROSINT to be adjusted.
Important information about taking TIROSINT: You should take TIROSINT exactly as your doctor tells you to take it. Your doctor will tell you how much TIROSINT to take each day. You should not stop taking TIROSINT or change your dose unless your doctor tells you to. Take TIROSINT once each day, on an empty stomach, approximately 30 minutes to 1 hour before breakfast. 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); and at least 4 hours before you take medicines that contain bile acid sequestrants or ion exchange resins. Ask your doctor if you are not sure whether any medicines you are taking may contain these ingredients. Your doctor should do certain blood tests while you are taking TIROSINT and may change your daily dose of TIROSINT as needed.
What are the possible side effects of TIROSINT? The most common side effects of TIROSINT include irregular heartbeat, chest pain, shortness of breath, leg cramps, headache, nervousness, irritability, sleep problems (insomnia), tremors, muscle weakness, change in appetite, weight loss, vomiting, diarrhea, sweating a lot, heat intolerance, fever, changes in menstrual period, and hives or skin rash. TIROSINT may cause serious side effects, including heart problems. Your risk for these problems may be greater if you are elderly, have heart problems, or if you take too much TIROSINT. Tell your doctor right away if you develop heart problems, as your doctor may choose to reduce your dose or stop treatment with TIROSINT. TIROSINT may also cause worsening of blood sugar control in diabetic patients and weak or brittle bones. Tell your doctor if you are diabetic or if you already have weak or brittle bones (osteoporosis) before taking TIROSINT. Partial hair loss may occur during the first months of treatment with TIROSINT. This is usually temporary and lasts a short period of time.
USE ONLY AS DIRECTED BY YOUR HEALTHCARE PROFESSIONAL. These are not all the possible side effects of TIROSINT. Talk to your healthcare provider or pharmacist for more information or for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or by visiting www.fda.gov/medwatch. For more dosing information, please see the accompanying full Prescribing Information and Patient Information.