⚠️ Mechanism
Calcium forms insoluble complexes with levothyroxine, reducing absorption.
📋 Effect
Reduced levothyroxine absorption; hypothyroid symptoms
💊 Management
Separate doses by at least 4 hours. Take levothyroxine on empty stomach.
Plain Language Summary
This interaction is considered moderate because calcium can interfere with how much levothyroxine your body absorbs. This reduction in absorption may lead to symptoms of an underactive thyroid. The data suggests separating these doses by at least four hours.
Source
Singh N et al. JAMA 2000; FDA levothyroxine labeling
Supporting Research
First-line drugs for hypertension
Beta-blockers for hypertension
Calcium channel blockers versus other classes of drugs for hypertension
Effect of early treatment with anti-hypertensive drugs on short and long-term mortality in patients with an acute cardiovascular event
Phlebotonics for venous insufficiency
Calcium channel blockers versus other classes of drugs for hypertension
Calcium supplementation for prevention of primary hypertension
Calcium supplementation for prevention of primary hypertension
Medical Disclaimer: This interaction record is for informational and educational purposes only and does not constitute medical advice. Drug-supplement interactions can be dangerous. Always consult your healthcare provider or pharmacist before combining any supplement with prescription medications. Do not stop or change any medication without professional guidance.