welche nebenwirkungen hat l-thyroxin — what symptoms are typical?

The provided context does not contain specific information about L-thyroxine (levothyroxine). Typical side effects are usually due to overtreatment and mirror hyperthyroidism: palpitations, tachycardia, nervousness, insomnia, tremor, increased sweating, weight loss, diarrhea, and heat intolerance. Headache, nausea, or allergic skin reactions may also occur. Chronic overdosing can lead to cardiac arrhythmias, osteoporosis (especially in postmenopausal women), or thyrotoxic crisis. Undertreatment causes hypothyroid symptoms like fatigue, cold intolerance, and constipation. L-thyroxine must be taken under medical supervision; dosage is adjusted based on TSH levels. Interactions with other drugs (e.g., iron, calcium, antacids) are relevant. The evidence is based on clinical practice, not on the provided sources.