In people with Graves' disease taking antithyroid medications, adding selenium may lead to faster normalization of thyroid hormone levels at six months, but this effect does not last until nine months and differs depending on the type and amount of selenium used.

In adults with Graves' disease taking antithyroid medication, taking selenium supplements at 100–300 μg per day for 3 to 6 months lowers levels of FT3 and FT4 hormones in the blood, but these reductions do not remain after 9 months of treatment.

Taking selenium supplements at 100–300 micrograms per day for 3 to 6 months may lead to a small rise in thyroid-stimulating hormone levels in adults with Graves' disease who are on antithyroid drugs, but this change does not continue after 6 months.

Taking selenium supplements daily at 100–300 micrograms for six months may lower levels of antibodies targeting the thyroid-stimulating hormone receptor in adults with Graves' disease who are on antithyroid drugs, but this reduction does not last beyond nine months.

Taking selenium supplements after standard treatment for Graves' disease does not reliably lead to better long-term remission, and blood levels of selenium do not predict whether the disease will return.

Taking selenium supplements does not lead to better quality of life for people with Graves' hyperthyroidism who do not have eye symptoms, as studies show no meaningful difference in mood or self-reported symptoms compared to taking a placebo.