Is lemon balm good for hyperthyroid ?

With the usuals: Lemon balm is related to mint. I would expect it to have a minor calming effect in the case of hyperthyroidism when taken with the usual hyperthyroid medications (ptu (propylthiouracil) or tapazole), not instead of them.

Not likely: If your thyroid is overactive, you need real medicine. Lemon balm may have a mild anti-anxiety effect, but it will not work as well as b-blockers or other meds for hyperthyroidism. On the other hand, lemon balm will not harm you, and you can take it if you want, unless taking it prevents you from getting needed treatment.