What is this drug used for?
• It is used to add thyroid hormone to the body.
• It is used to manage thyroid cancer.
• It may be given to you for other reasons. Talk with the doctor.
Frequently reported side effects of this drug
• Hair loss
Other side effects of this drug: Talk with your doctor right away if you have any of these signs of:
• Chest pain
• Fast heartbeat
• Abnormal heartbeat
• Passing out
• Vision changes
• Shortness of breath
• Loss of strength and energy
• Lack of appetite
• Increased appetite
• Excessive weight gain or loss
• Swelling of arms or legs
• Abdominal cramps
• Emotional instability
• Trouble sleeping
• Temperature sensitivity
• Sweating a lot
• Muscle cramps
• Muscle weakness
• Bone pain
• Menstrual irregularities
• Signs of a significant reaction like wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat.
Note: This is not a comprehensive list of all side effects. Talk to your doctor if you have questions.
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Medication Safety Issues
Levothyroxine may be confused with lamoTRIgine, Lanoxin, levoFLOXacin, liothyronine
Levoxyl may be confused with Lanoxin, Levaquin, Luvox
Synthroid may be confused with Symmetrel
Significant differences exist between oral and IV dosing. Use caution when converting from one route of administration to another.
Other safety concerns:
To avoid errors due to misinterpretation of a decimal point, always express dosage in mcg (not mg).
Generic Availability: US
May be product dependent
Storage and Stability
Capsules and tablets: Store at 25°C (77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F). Protect from heat, light, and moisture.
Oral solution (Tirosint): Store in original container (closed aluminum pouch) at 25°C (77°F); excursions are permitted between 15°C and 30°C (59°F and 86°F). Keep ampules in pouch until ready to use; after opening the pouch, all ampules in the pouch should be used within 15 days.
Injection: Store at 20°C to 25°C (68°F to 77°F). Protect from light.
Additional stability data:
Stability in polypropylene syringes (100 mcg/mL in NS) at 5°C ± 1°C is 7 days (Gupta 2000).
Stability in latex-free, PVC minibags protected from light and stored at 15°C to 30°C (59°F to 86°F) was 12 hours for a 2 mcg/mL concentration or 18 hours for a 0.4 mcg/mL concentration in NS. May be exposed to light; however, stability time is significantly reduced, especially for the 2 mcg/mL concentration (Strong 2010).
Adverse reactions 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
Rare but important or life-threatening: Dysgeusia (Syed 2016), seizure