ADVERSE REACTIONS
Adverse reactions associated with levothyroxine therapy are primarily those of hyperthyroidism due to therapeutic overdosage. They include the following:
General: fatigue, increased appetite, weight loss, heat intolerance, fever, excessive sweating;
Central nervous system: headache, hyperactivity, nervousness, anxiety, irritability, emotional lability, insomnia;
Musculoskeletal: tremors, muscle weakness;
Cardiac: palpitations, tachycardia, arrhythmias, increased pulse and blood pressure, heart failure, angina, myocardial infarction, cardiac arrest;
Pulmonary: dyspnea;
GI: diarrhea, vomiting, abdominal cramps;
Dermatologic: hair loss, flushing;
Reproductive: menstrual irregularities, impaired fertility.
Pseudotumor cerebri and slipped capital femoral epiphysis have been reported in children receiving levothyroxine therapy. Overtreatment may result in craniosynostosis in infants and premature closure of the epiphyses in children with resultant compromised adult height.
Seizures have been reported rarely with the institution of levothyroxine therapy.
Inadequate levothyroxine dosage will produce or fail to ameliorate the signs and symptoms of hypothyroidism.
Hypersensitivity reactions to inactive ingredients have occurred in patients treated with thyroid hormone products. These include urticaria, pruritus, skin rash, flushing, angioedema, various GI symptoms (abdominal pain, nausea, vomiting and diarrhea), fever, arthralgia, serum sickness and wheezing. Hypersensitivity to levothyroxine itself is not known to occur.
In addition to the above events, the following have been reported, predominately when Levoxyl® tablets were not taken with water: choking, gagging, tablet stuck in throat and dysphagia (see Information for Patients).
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