welche nebenwirkungen hat l-thyroxin — when to see a doctor?

L-Thyroxine (levothyroxine) is a thyroid hormone replacement for hypothyroidism. Side effects usually result from overmedication and mimic hyperthyroidism: palpitations, tachycardia, anxiety, insomnia, sweating, weight loss, diarrhea. Rarely, allergic reactions (rash, itching) or exacerbation of heart conditions occur. See a doctor immediately if you experience: chest pain, irregular heartbeat, shortness of breath, unexplained rapid weight loss, persistent nausea/vomiting, or signs of an allergic reaction (facial swelling, difficulty breathing). Also consult if hypothyroid symptoms (fatigue, weight gain) persist despite treatment, as dose adjustment may be needed. Dosing is individualized; regular blood tests (TSH, fT3, fT4) are essential. Note: This is not medical advice. Always consult a physician for specific concerns. Evidence is based on clinical practice and guidelines, not on the provided context.