GENERIC NAME: LEVOTHYROXINE - INJECTION (lev-oh-thigh-ROX in)
BRAND NAME(S): Levothroid, Synthroid
WARNING: This medication should not be used for weight loss. Normal doses of this medication will not cause weight loss in people with normal thyroid function. Large doses of this medication may cause very serious (possibly fatal) side effects, especially when taken with diet pills.
USES: Levothyroxine is used to treat an underactive thyroid (hypothyroidism). It is a man-made substance that replaces the natural substance (thyroid hormone) that is normally produced by the thyroid gland. Low thyroid hormone levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. Having enough thyroid hormone in your bloodstream is important for maintaining normal mental and physical activity. In children, having enough thyroid hormone is important for normal mental and physical development.This medication is also used to treat other types of thyroid disorders (e.g., certain types of goiters, thyroid cancer). It is also used to test thyroid activity.
HOW TO USE: This medication is given by injection into a vein or into a muscle as directed by your doctor, usually once a day. Dosage is based on your medical condition, thyroid hormone levels, and response to treatment.If you are giving this medication to yourself at home, learn all preparation and usage instructions from your health care professional. Use this medication immediately after mixing. Before using, check this product visually for particles or discoloration. If either is present, do not use the liquid. Learn how to store and discard medical supplies safely.Use this medication regularly in order to get the most benefit from it. To help you remember, use it at the same time each day. Do not stop using this medication without consulting with your doctor. Thyroid replacement treatment is usually taken for life.Symptoms of low thyroid levels include tiredness, muscle aches, constipation, dry skin, weight gain, slow heartbeat, or sensitivity to cold. These symptoms should improve in a few days as your body adjusts to this medication. Tell your doctor if your symptoms persist or worsen.
SIDE EFFECTS: Some hair loss may occur during the first few months of starting this drug. This effect is usually temporary as your body adjusts to this medication. If this effect persists or worsens, tell your doctor or pharmacist promptly.Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Though unlikely, it is possible to have too much thyroid hormone. Your doctor may need to reduce the dose of this medication. Tell your doctor immediately if any of these unlikely but serious signs of too much thyroid hormone occur: headache, mental/mood changes (e.g., nervousness, irritability), shaking, sweating, sensitivity to heat, diarrhea, weight loss, trouble sleeping, tiredness.Get medical help right away if any of these rare but very serious side effects occur: chest pain, shortness of breath, fast/pounding/irregular heartbeat, swelling of the hands/feet, seizures.A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
PRECAUTIONS: Before using levothyroxine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: a certain overactive thyroid condition (thyrotoxicosis), a recent heart attack (acute myocardial infarction), adrenal gland problem (uncorrected adrenal insufficiency).Do not use thyroid drugs for weight control.Before using this medication, tell your doctor or pharmacist your medical history, especially of: heart problems (e.g., angina, heart failure, irregular heartbeat), high blood pressure, diabetes (diabetes mellitus), water diabetes (diabetes insipidus), other hormone disorders (e.g., decreased pituitary hormone).If you have diabetes, this drug may make it harder to control your blood sugar levels. Check your blood sugar regularly as directed by your doctor. Tell your doctor immediately if you have symptoms such as increased thirst/urination, shakiness, unusual sweating, dizziness, or hunger. Your anti-diabetic medication or diet may need to be adjusted.Before having surgery, tell your doctor or dentist that you are taking this medication.Caution is advised when using this drug in the elderly because they may be more sensitive to its effects on the heart if there is too much thyroid hormone.Caution is advised when using this drug in children because overuse may keep the child from reaching full adult height. Consult your doctor for more details.Current information shows that this drug may be used during pregnancy. Tell your doctor if you are pregnant or if you become pregnant because your dose may need to be adjusted.Small amounts of this drug pass into breast milk. While there have been no reports of harm to nursing infants, consult your doctor before breast-feeding.
DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.Some products that may interact with this drug include: androgens/anabolic steroids (e.g., testosterone), antidepressants (e.g., SSRIs such as sertraline, tricyclics such as amitriptyline), beta blockers (e.g., propranolol), corticosteroids (e.g., dexamethasone), cytokines (e.g., interferon alfa, interleukin-2), digoxin, epinephrine, ketamine, theophylline, warfarin, drugs that can decrease thyroid hormone levels (e.g., amiodarone, medications containing iodide/iodine, lithium), drugs affecting liver enzymes that remove levothyroxine from your body (e.g., phenobarbital, rifamycins including rifampin, certain anti-seizure medicines including carbamazepine and phenytoin).High doses of salicylates (e.g., high doses of aspirin) may affect thyroid hormone levels in the blood. However, low-dose aspirin should be continued if prescribed by your doctor for specific medical reasons such as heart attack or stroke prevention (usually at dosages of 81-325 milligrams per day). Ask your doctor or pharmacist for more details.Check the labels on all your medicines (e.g., cough-and-cold products, diet aids) because they may contain ingredients such as decongestants or caffeine that could increase your heart rate or blood pressure. Ask your pharmacist about using those products safely.
OVERDOSE: If overdose is suspected, contact a poison control center or emergency room immediately. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: fast/irregular heartbeat, chest pain, confusion, loss of consciousness.
NOTES: Do not share this medication with others.Laboratory and/or medical tests (e.g., thyroid function tests) should be performed periodically to monitor your progress or check for side effects. Some of the drugs listed in the Drug Interactions section can interfere with thyroid function tests, possibly causing false test results. Consult your doctor or laboratory personnel for more details.
MISSED DOSE: For the best possible benefit, it is important to receive each scheduled dose of this medication as directed. If you miss a dose, contact your doctor or pharmacist immediately to establish a new dosing schedule. Do not double the dose to catch up.
STORAGE: Store at room temperature away from light and moisture. After mixing, discard any unused portion. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.
Information last revised March 2013. Copyright(c) 2013 First Databank, Inc.
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