Supplements and Thyroid hormone

Multivitamins with calcium or iron can reduce levothyroxine absorption. If your multivitamin contains calcium, iron or magnesium, keep it at least 4 hours from your thyroid medication, as for those minerals on their own.

Calcium reduces levothyroxine absorption. Calcium binds levothyroxine in the gut and can lower thyroid hormone levels. Keep it at least 4 hours away from your thyroid medication.

Iron reduces levothyroxine absorption. Iron binds levothyroxine in the gut and can lower thyroid hormone levels. Keep it at least 4 hours away from your thyroid medication.

Magnesium reduces levothyroxine absorption. Magnesium binds levothyroxine in the gut and can lower thyroid hormone levels. Keep it at least 4 hours away from your thyroid medication.

Ashwagandha may raise thyroid hormone levels. Ashwagandha has increased T3/T4 in some studies. Combined with thyroid medication, this could push levels too high — get your levels checked.

Fiber can reduce levothyroxine absorption. Dietary fiber can lower how much levothyroxine you absorb. Keep psyllium well away from your thyroid medication — we use 4 hours, as for calcium and iron — and follow your prescriber's advice.

Extra iodine can disrupt thyroid treatment. Iodine supplements can push thyroid function in either direction. Only take them if your doctor agrees.

Biotin distorts thyroid blood tests. High-dose biotin can make thyroid lab results look falsely abnormal, which may lead to a wrong dose change. Stop it several days before tests.

The calcium in Ca-AKG reduces levothyroxine absorption. Ca-AKG is a calcium salt, and calcium binds levothyroxine in the gut. Keep it at least 4 hours away from your thyroid medication.