Iodine and Levothyroxine: interaction, severity and spacing
Iodine and Levothyroxine interact because supplemental iodine can unmask or worsen autoimmune thyroid disease and shift thyroid hormone requirements. Take them with care. Moderate risk.
The interaction in detail
| Pair | Iodine and Levothyroxine |
|---|---|
| Type | Nutrient–drug interaction |
| Severity | Moderate |
| Required spacing | None specified |
| Onset | At the time of dosing |
Mechanism
Supplemental iodine can unmask or worsen autoimmune thyroid disease and shift thyroid hormone requirements.
What to do
Do not add iodine supplements while on levothyroxine without lab monitoring.
How to fit both into one day
Take iodine with food and keep the dose steady. Excess iodine can shift thyroid function in either direction.
Levothyroxine needs an empty stomach and gastric acid for full absorption. Take it 30-60 minutes before breakfast with plain water, and keep calcium, iron and coffee at least 4 hours away.
Putting Iodine in the morning and Levothyroxine in the morning satisfies the 0-hour separation without disrupting either one's absorption window.