Levothyroxine, while generally safe, can cause side effects. Common ones include changes in heart rate (faster or slower), weight changes, nervousness, tremors, insomnia, and digestive issues like diarrhea or constipation. Less common, but serious, side effects require immediate medical attention: chest pain, shortness of breath, and allergic reactions (rash, swelling, difficulty breathing).
Medication Interactions
Levothyroxine interacts with many medications. Certain antacids, calcium supplements, iron supplements, and cholestyramine can reduce levothyroxine absorption. Take levothyroxine at least four hours before or after taking these medications. Similarly, medications that affect the liver (like some antibiotics) can alter levothyroxine metabolism, potentially requiring dosage adjustments. Always inform your doctor about all medications, supplements, and herbal remedies you’re taking. This includes over-the-counter drugs. Regular blood tests monitor thyroid hormone levels and ensure the correct dosage.
Specific Interactions
Soy products and high-fiber foods can also interfere with absorption. Discuss dietary changes with your doctor, especially if experiencing inconsistent medication effects. Pregnancy and breastfeeding significantly alter thyroid hormone needs and require close medical supervision and potential dosage adjustments. Never adjust your dose without your doctor’s guidance.
