Iron × Levothyroxine

Severity: MODERATE Evidence: well-established

Mechanism

Iron forms insoluble complexes with levothyroxine, reducing absorption.

Effect

Reduced levothyroxine absorption; hypothyroid symptoms

Management

Separate doses by at least 4 hours.

Source

Campbell NR et al. BMJ 1992

⚠️ 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.