MAJOR — Use With Caution
🔴 CAUTION — Major interaction between Calcium and Levothyroxine. Avoid unless under direct medical supervision.
Evidence level: STRONG
Calcium supplements block thyroid medication absorption. Take at least 4 hours apart.
Calcium chelates levothyroxine in GI tract, significantly reducing absorption.
Take levothyroxine on an empty stomach first thing in the morning. Wait at least 4 hours before taking calcium supplements. This is essential for your thyroid medication to work properly.
Take levothyroxine on an empty stomach, 30-60 minutes before breakfast. Take supplements at least 4 hours later to be safe.
Risk may increase with: older age, liver or kidney impairment, taking multiple medications, and higher doses of either substance.
Your medication may not be working properly. For antibiotics: infection not improving. For thyroid meds: fatigue, weight gain, cold sensitivity returning.
Ask your doctor: "Is there a safer alternative to Calcium that I can take with Levothyroxine?" Bring a list of ALL supplements and medications you take.
Thyroid medications are sensitive to absorption interference. Take levothyroxine on an empty stomach, 30-60 minutes before food or other supplements. Space calcium, iron, and antacids at least 4 hours away. Selenium and zinc are generally safe thyroid-supporting nutrients.
Calcium supplements block thyroid medication absorption. Take at least 4 hours apart.
Take levothyroxine on an empty stomach, 30-60 minutes before breakfast. Take supplements at least 4 hours later to be safe.
Your medication may not be working properly. For antibiotics: infection not improving. For thyroid meds: fatigue, weight gain, cold sensitivity returning.
Thyroid medications are sensitive to absorption interference. Take levothyroxine on an empty stomach, 30-60 minutes before food or other supplements. Space calcium, iron, and antacids at least 4 hours away. Selenium and zinc are generally safe thyroid-supporting nutrients.
Ask your doctor: "Is there a safer alternative to Calcium that I can take with Levothyroxine?" Bring a list of ALL supplements and medications you take.
Or browse the full interaction database (121,000+ pairs).