Levothyroxine Side Effects
Common and serious side effects of Levothyroxine (Levothyroxine Sodium) — what to expect and how to manage them.
Common Side Effects
- Usually well-tolerated at correct dose
- Symptoms of over-replacement: palpitations, sweating, anxiety, insomnia, weight loss, diarrhea, tremor
- Hair loss (usually temporary during dose adjustment)
Serious Side Effects
Seek immediate care if severe- Atrial fibrillation (from over-replacement — especially in elderly and those with cardiac disease)
- Bone density loss (from long-term over-replacement)
- Adrenal crisis if thyroid replaced too rapidly in adrenal insufficiency
Managing Side Effects
- Take on empty stomach 30-60 minutes before breakfast or 4 hours after last meal — absorption is significantly affected by food
- Consistent timing is critical — take at same time daily
- Many medications and supplements interfere: calcium, iron, PPI antacids, soy — take 4 hours apart
- Symptoms of over-replacement (fast heartbeat, anxiety) mean dose is too high — call doctor
What Your Doctor May Monitor
TSH (recheck 6-8 weeks after any dose change, then every 6-12 months)T4 levelsHeart rate and rhythmBone density (long-term, especially post-menopausal women)
Levothyroxine Cash Price
Levothyroxine cash prices start from $11 when pharmacies compete on Script Unlock — up to 65% below retail. No insurance required.
Compare Levothyroxine PricesMedical Disclaimer: This information is for educational reference only. Side effects vary by individual, dose, and other medications. Always consult your healthcare provider for personalized medical advice. Do not stop or change your medication without medical guidance.