Because of the importance of thyroid hormones, treatment of the disease is difficult. Mild cases can often be treated with beta blockers, which alleviate the symptoms of high thyroid levels such as tachycardia and nausea. The next stage of treatment are drugs that suppress the production of the hormone. However, when this treatment fails, radioactive iodine is used to destroy a part of the thyroid. If this fails, the final intervention is surgical removal of the thyroid followed by hormone replacement treatment.