What is this medication?
Officially indicated for use in hypothyroidism and pituitary thyrotropin-stimulating hormone suppression.
“ALERT: US Boxed Warning
Thyroid hormones, including levothyroxine, 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.”
How does this medication work?
Levothyroxine (T4) is a synthetic form of thyroxine which is an endogenous hormone produced by the thyroid gland to regulate the body’s metabolism. T4 is converted to its active metabolite L-triiodothyronine (T3). Both T4 and T3 bind to thyroid receptors in the cell nucleus and regulate cellular metabolic rate through DNA transcription and protein synthesis.
How should I take this medication?
Primary hypothyroidism: Start with an initial dose of 12 to 25 mcg once daily and adjust the dose every 3 to 6 weeks based on clinical response and serum TSH and/or free T4 serum concentration until TSH is normalized.
How to Take: Take in the morning on an empty stomach at least 30 minutes before food. Alternatively, you can take at night 3 to 4 hours after your last meal. Do not take within 4 hours of a calcium or iron containing food/supplement. Take the medication exactly as prescribed by your doctor at the same time each day.
Do Not Use Levothyroxine, Synthroid/Eltroxin/Levoxyl: Never use if you have an uncorrected adrenal insufficiency; hypersensitivity; untreated thyrotoxicosis, overt thyrotoxicosis; acute myocardial infarction, acute myocarditis or acute pancarditis.
Can You Take Levothyroxine, Synthroid/Eltroxin/Levoxyl When Pregnant: It is safe to use during pregnancy as Levothyroxine, Synthroid/Eltroxin/Levoxyl have shown to not increase the risk of congenital abnormalities or miscarriage. Instead, thyroid replacement therapy minimizes the risk of adverse pregnancy outcomes in female with overt hypothyroidism and treatment is recommended during pregnancy.
What should I watch for while using this medication?
Use with caution in patients with adrenal insufficiency
Never use with patients with benign thyroid nodules
Never use in post-menopausal women, elderly, patients with cardiovascular disease, osteoporosis, large thyroid nodules, or long-standing goiters, or low-normal TSH levels
Use with caution in patients with heart failure
Use with caution in patients with diabetes
What if I miss a dose?
If you miss a dose, make sure to take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
How should I store this medication?
Keep out of the reach of children at all times. Store at room temperature, 59 to 86° F (15 to 30° C). Protect from light. Keep the container tightly closed. Properly dispose of any unused medication after the expiration date.
What are the possible side effects of using this medication?
Adverse reactions/side effects are primarily those of hyperthyroidism due to therapeutic overdosage.
Cardiovascular: Angina pectoris, cardiac arrhythmia, cardiac failure, flushing, increased blood pressure, increased pulse, myocardial infarction, palpitations, tachycardia
Central nervous system: Anxiety, emotional lability, fatigue, headache, heat intolerance, hyperactivity, insomnia, irritability, myasthenia, nervousness, pseudotumor cerebri (children)
Dermatologic: Alopecia, diaphoresis, skin rash
Endocrine & metabolic: Goiter (exophthalmic; IV), menstrual disease, weight loss
Gastrointestinal: Abdominal cramps, diarrhea, increased appetite, vomiting
Genitourinary: Reduced fertility
Hepatic: Increased liver enzymes
Neuromuscular & skeletal: Decreased bone mineral density, muscle spasm, slipped capital femoral epiphysis (children), tremor
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