Lugol's Iodine vs. Potassium Iodide: What's the Difference?

Potassium Iodide (KI) shows up on pharmacy shelves and in supplement aisles alike, which leads to a lot of questions about how it relates to Lugol's Solution.

The Short Answer

Lugol's Solution already contains potassium iodide as one of its two active ingredients (alongside elemental iodine). A standalone Potassium Iodide Solution contains only the potassium iodide component.

Lugol's Solution vs. Potassium Iodide Solution

What Potassium Iodide Is

Potassium iodide is a simple salt made of potassium and iodide, much like table salt is made of sodium and chloride. It's a white, crystalline solid that dissolves easily in water to make a clear, colorless solution. Iodide is the form of iodine the body absorbs and the thyroid uses, which is why potassium iodide (or the closely related potassium iodate) is also the compound used to iodize table salt. See How Salt Fortification Works.

How Lugol's Solution Is Different

Lugol's Solution pairs potassium iodide with molecular iodine. In water, the two combine to form triiodide, which keeps the iodine dissolved and gives the solution its deep amber-brown color. So a bottle of Lugol's contains iodine in two forms, while a potassium iodide solution contains iodide only. See Molecular Iodine vs. Iodide and Potassium Iodide as a Stabilizer.

Practical Differences

• Color: Lugol's is amber-brown and can stain; potassium iodide solution is clear and doesn't stain.
• Taste: Lugol's has a strong, metallic taste; potassium iodide tastes salty and slightly bitter.
• Strengths: our Lugol's comes in six strengths from 2% to 20%; our potassium iodide solution is a 2% strength.
• Per drop: the same percentage doesn't mean the same iodine per drop across the two products. Compare amounts per serving on each Supplement Facts panel.

Choosing Between Them

Most people new to iodine drops start with Lugol's Solution because it's the traditional formula with the widest range of strengths. Others prefer a single-ingredient iodide product for simplicity or because a healthcare provider suggested one. Either way, follow the label and talk with a healthcare provider before starting, especially if you're pregnant, nursing or taking thyroid medication.

Frequently Asked Questions

Is Potassium Iodide the same thing as Lugol's Solution?

No. Potassium Iodide Solution is a single-ingredient formula, while Lugol's Solution combines potassium iodide with elemental iodine.

Why do some people prefer Potassium Iodide over Lugol's?

Some people prefer a single-ingredient formula for simplicity, or have a specific protocol calling for potassium iodide alone.

Which one should I choose if I'm new to iodine supplementation?

Most newcomers start with Lugol's Solution, since it's the time-tested formula the category is built around.

Shop Lugol's Solution — the traditional, trusted way people have supported their iodine intake for over 200 years.

This article is for general educational purposes only and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease, and is not a substitute for advice from a qualified healthcare provider — especially if you are pregnant, nursing, taking thyroid medication, or managing a thyroid condition.

Lauren Mitchell breaks down iodine compound differences and label terminology for the Iodine Journal.

This article is part of our complete comparison guide to Lugol's Solution, Liquid Iodine, and Nascent Iodine.