Levothyroxine overdose symptoms
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Common Symptoms of Levothyroxine Overdose
Levothyroxine overdose can cause a range of symptoms, which may vary depending on the amount ingested, the patient’s age, and underlying health conditions. Commonly reported symptoms include lethargy, tremors, body temperature dysregulation (such as fever or flushing), orthostatic hypotension, diarrhea, palpitations, increased sweating, irritability, anxiety, and increased bowel movements. Some patients may also experience tachycardia (fast heart rate), hypertension, and cardiac arrhythmias. In children, symptoms like fever, flushing, palpitations, increased sweating, tremors, irritability, and even convulsions have been observed. Psychiatric symptoms such as agitation, anxiety, and suicidal ideation can also be exacerbated by overdose, especially in those with pre-existing mental health conditions 12567.
Severe and Rare Complications
While most cases of levothyroxine overdose are mild and resolve without intervention, severe complications can occur. These include thyroid storm (a life-threatening form of thyrotoxicosis), seizures, coma, and significant cardiac issues such as arrhythmias. There have been reports of prolonged coma, delirium, and even hair loss and skin peeling (desquamation) following massive overdoses. However, these severe outcomes are rare, and most patients recover fully with supportive care 4567.
Delayed Onset and Duration of Symptoms
Symptoms of levothyroxine overdose may not appear immediately. Due to the long half-life of levothyroxine (about 7 days), the onset of symptoms can be delayed for several days, sometimes up to 11 days after ingestion. Late-onset symptoms are common, and monitoring is recommended for several days after a suspected overdose. Most symptoms resolve spontaneously over time, and long-term complications are uncommon 23458.
Dose-Response Relationship and Individual Variation
The severity of symptoms does not always correlate with the ingested dose. Some individuals may remain asymptomatic even after ingesting large amounts (up to 9 mg or more), while others may develop symptoms after lower doses. Factors such as age, metabolism, co-ingested substances, and underlying health conditions can influence the clinical presentation. Children and elderly patients, or those with comorbidities, may be more susceptible to toxicity at lower doses 356810.
Management and Treatment of Overdose
There is no standardized protocol for treating levothyroxine overdose. Most cases are managed by discontinuing the drug and providing supportive care. Beta-blockers, especially propranolol, are commonly used to control symptoms like tachycardia and tremors. In more severe cases, treatments such as cholestyramine, glucocorticoids, and, rarely, extractive techniques (like charcoal hemoperfusion or plasmapheresis) may be considered. Antithyroid drugs and activated charcoal are generally not effective. Most patients recover without the need for aggressive interventions 124678.
Conclusion
Levothyroxine overdose most often results in mild, self-limiting symptoms such as tremors, palpitations, and gastrointestinal upset, but can occasionally lead to severe complications like seizures, arrhythmias, or coma. The onset of symptoms may be delayed, and the severity does not always depend on the dose ingested. Most cases resolve with supportive care, and close monitoring is recommended, especially in children, elderly patients, or those with underlying health issues.
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