A complete safety, timing, and dosage guide for combining St. John's Wort with Iodine — including how the two supplements interact, the best time of day to take each, and which populations should be careful.
Yes, you can safely take iodine and St. John's Wort together. There is no significant interaction between these two supplements.
Iodine and St. John's Wort together are a safe, neutral combination. St. John's Wort does not affect how your body absorbs or uses iodine, and iodine is unlikely to alter the effects of St. John's Wort. You can take both as directed, but always tell your doctor about all supplements you use.
Iodine is a trace mineral absorbed in the upper small intestine and transported to the thyroid gland, where it is used to make thyroid hormones. St. John's Wort is an herbal extract that works primarily by increasing brain levels of serotonin, dopamine and norepinephrine. It also strongly induces cytochrome P450 enzymes, particularly CYP3A4 and CYP2C19, and the drug transporter P-glycoprotein. However, iodine is not metabolized by these enzymes and does not compete for the same transport proteins or receptors. As a result, there is no plausible biological mechanism by which St. John's Wort would change iodine uptake or thyroid hormone synthesis.
If you need both supplements, the simplest approach is to take them together with your breakfast. Use iodine as a standalone tablet or as part of a multivitamin. For St. John's Wort, select a standardized extract containing 0.3% hypericin. If you miss a dose, skip the missed dose and continue with your next scheduled time—do not double up. Taking both with food can reduce any stomach irritation and make the habit easier to remember.
Iodine is available as potassium iodide, sodium iodide, or as part of kelp supplements. St. John's Wort is usually standardized to hypericin or hyperforin content. The form of iodine you take does not change its interaction profile with St. John's Wort. However, kelp-based iodine supplements can contain variable amounts of iodine, so if you are combining with St. John's Wort, choose a precisely dosed tablet for predictable intake.
Yes, you can take them together at the same time. They don't affect each other's absorption or function, so no separation is needed. I take both at breakfast with a glass of water.
Yes, it is safe to combine them daily. There is no evidence that taking both each day causes any negative health effects. However, stick to recommended doses and check with your doctor if you take any prescription medications.
You do not need to wait between iodine and St. John's Wort. There is no interaction, so you can take them at the same time or any time of day.
No, they do not compete for absorption. Iodine is absorbed via sodium-iodide symporters in the gut, while St. John's Wort's active compounds are absorbed by simple diffusion, so they don't interfere with each other.
Most people can take them together safely, but you should avoid the combination if you are on any medication that St. John's Wort interferes with, including antidepressants, birth control pills, or blood thinners. If you have thyroid disease or are pregnant, consult your doctor before taking iodine. Avoid iodine supplements if you have a known iodine allergy.
You can take both with food. Taking iodine with food helps prevent stomach upset, and St. John's Wort is often better tolerated with meals. If you prefer, you can take them on an empty stomach as well, unless you notice any discomfort.
Reviewed by Caroline M. on April 13, 2026 for accuracy against the sources listed above. This page is educational and is not a substitute for professional medical advice.
The matrix has 86 supplements and 7310 pairwise interactions. Click any cell to see the full breakdown.