Lugol's Solution Simply Explained

1. What Is Lugol's Solution?

Lugol's solution is a mixture of iodine and potassium iodide in water. Classically it contains 5 % iodine and 10 % potassium iodide, but there are also weaker dilutions. Closely related is saturated potassium iodide solution, or SSKI for short. Both deliver much more iodine than one takes in daily with food. Iodine doses in tiny amounts, as in iodized salt, are not included.

2. Where Is It Found, and What Is It Made From?

The solution itself does not exist in nature. It is made by dissolving iodine in a potassium iodide solution. The potassium iodide ensures that the iodine dissolves in water at all. The iodine for this comes from seawater, marine algae, iodine-containing brines and from the mother liquor in the extraction of Chile saltpeter.

3. What Does Lugol's Solution Do? What Research Shows

Hyperthyroidism and Graves' Disease

In hyperthyroidism due to Graves' disease, Lugol's solution was studied before surgery. There, in a study with randomization, it lowered thyroid hormones 8. In another study, the hormones fell too far in some of those treated 12. A study with saturated potassium iodide solution found no difference in thyroid status after radioiodine therapy 13. The strength of evidence is moderate, the groups were mostly small.

Preparation for Thyroid Surgery

Before thyroid surgery, Lugol's solution was also tested. Two studies found less blood loss during surgery 610. Three other studies found no difference here 5812. The strength of evidence is moderate, and the studies were altogether small. For saturated potassium iodide solution there is only one observational study 20. Which patients and which dosage really benefit is open.

Breast Tissue and Breast Pain

In breast pain and fibrocystic changes, that is benign tissue changes, molecular iodine was studied. A randomized (participants assigned by lot) study showed an improvement in pain, tenderness and nodularity compared with placebo (sham agent) 3. However, what was tested was not Lugol's solution or potassium iodide, but molecular iodine. The strength of evidence is moderate. Dose, duration and transferability to other iodine preparations remain open.

Thyroid Protection from Radiation

For protection of the thyroid after nuclear accidents, potassium iodide tablets were studied. A review found evidence of a reduced risk of thyroid cancer in children, with low quality of evidence 1. A controlled study (with comparison group) in healthy volunteers found a lower radiation dose to the thyroid for high-dose potassium iodide 14. In comparison, potassium iodide did not perform better than sodium perchlorate 14. The strength of evidence is unclear, especially for children and with longer administration.

Infections

For infections, a comparison with a sham agent or with other agents is lacking. A randomized study in patients with cutaneous sporotrichosis, a skin infection, found no difference in healing rate and relapse between one and three daily doses 11. A review of high-dose potassium iodide in cutaneous sporotrichosis comes to no clear result 2. The strength of evidence is unclear. Whether and at what dosage potassium iodide works here at all remains open.

Other Outcomes

For further measured values, the studies show a mixed picture with low strength of evidence. A randomized study with Lugol's solution before surgery in Graves' disease found no difference in blood flow in the tissue 8. In cutaneous sporotrichosis, the side effects did not differ between once and three times daily administration of saturated potassium iodide solution 11. A controlled study in previous iodine-induced hyperthyroidism found no difference in the thyroid hormones T4 and T3, but in some the TSH rose significantly 16. Iodine from potassium iodide was better absorbed and excreted than from a kombu preparation 15.

4. How Was Lugol's Solution Taken in the Studies?

Lugol's solution was mostly given before operations in Graves' disease and thyroid surgery, sometimes in addition to radioiodine therapy. Saturated potassium iodide solution and high-dose potassium iodide were used in hyperthyroidism, after radioiodine, in radiation exposure, in cutaneous sporotrichosis and in studies on iodine excretion. Molecular iodine was also studied. The exact doses are shown in the table.

5. Is Lugol's Solution Safe? Side Effects in the Studies

The studies report predominantly good tolerability, with frequently mild and temporary complaints 3411. With saturated potassium iodide solution, side effects occurred frequently but mildly, without a difference between once and three times daily administration 11. After thyroid surgery, patients with Lugol's solution in a large observational study needed calcium short-term more often 18. In another observational study, vocal cord nerve paralysis and hypoparathyroidism occurred more often, while bruises on the neck occurred less often 19.

All details with tables and sources: full expert page on Lugol's solution