Calcium × Levothyroxine

Severity: MODERATE Evidence: well-established

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.

Source

Singh N et al. JAMA 2000; FDA levothyroxine labeling

⚠️ MODERATE INTERACTION: Monitor closely if this combination is used.

Disclaimer

This interaction record is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider before starting or stopping any supplement or medication.