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Thyroid surgery (thyroidectomy) for an overactive thyroid: when, risks and recovery

When thyroidectomy is advised for Graves' disease or toxic nodules, preparing with Neo-Mercazole (carbimazole), the risks to voice and calcium, the scar, recovery and lifelong levothyroxine.

Illustration: a closed surgical instrument tray with a folded drape and surgical gloves.

Removing the thyroid fixes an overactive thyroid quickly and almost always for good, at the price of an operation and lifelong levothyroxine. Neo-Mercazole (carbimazole) usually plays a part beforehand, bringing hormone levels to normal so surgery is safe.

Key points

  • When it is advised: large goitres pressing on the windpipe or gullet, suspected cancer, Graves’ disease that keeps returning (especially with eye disease), or when radioiodine and tablets do not suit.
  • Before surgery: carbimazole or methimazole until thyroid levels are normal.
  • Risks: a hoarse voice (permanent in about 1% to 2%) and low calcium from parathyroid damage.
  • Afterwards: usually one to two days in hospital, then lifelong levothyroxine after a total thyroidectomy.

When surgery is the right choice

The British Thyroid Foundation describes surgery as the usual choice for younger people with large goitres or severe disease, and as an option when Graves’ disease returns after tablets. NICE recommends total thyroidectomy first for adults with Graves’ disease when there are concerns about compression, cancer is suspected, or radioiodine and tablets are unsuitable. For a single toxic nodule, NICE offers radioiodine or removing half the thyroid (hemithyroidectomy).

Surgery has two practical advantages. It works fast, and, unlike radioiodine, there is no need to delay a pregnancy or fathering a child, NICE notes. In trials it also had the lowest relapse rate: 3% to 8% in a Swedish randomised study and about 10% in a network meta-analysis.

Getting ready

The Neo-Mercazole product information says carbimazole is given before thyroidectomy in a dose and for long enough to make you euthyroid (normal thyroid levels), and is stopped once surgery is done. NICE also recommends antithyroid tablets for anyone waiting for surgery.

Before the operation you may have blood tests including calcium, vitamin D and parathyroid hormone, and your vocal cords are usually checked. Choose an experienced surgeon who operates on thyroids regularly, and ask about their results.

The operation and its risks

It is done under general anaesthetic. A total thyroidectomy removes the whole gland; a lobectomy (hemithyroidectomy) removes one side.

  • Voice: some hoarseness is common and usually temporary. If the nerve to the voice box is damaged, the voice can be husky or weak; this usually recovers within six months, and permanent problems affect about 1% to 2% of people, according to the British Thyroid Foundation.
  • Calcium: the four parathyroid glands sit next to the thyroid and control calcium. Their blood supply can be disturbed, causing low calcium (hypoparathyroidism), which may be temporary or, less often, permanent.
  • Scar: usually hard to see once healed. Some people develop a raised (keloid) scar, which can be treated.

Recovery and follow-up

Most people stay in hospital for one to two days. After a total thyroidectomy you will take levothyroxine for life, usually starting straight away, with a thyroid blood test about six to eight weeks later to fine-tune the dose. NICE suggests TSH and free T4 checks at 2 and 6 months after a hemithyroidectomy, then yearly, because the remaining half may not keep up.

Once your thyroid levels are normal, you may need to eat less than you did while overactive to avoid gaining weight.

Tablets in the meantime

While you wait for surgery, keep taking the carbimazole or methimazole you are prescribed. Carbimazole is listed by PockDose, Yasabai and VGR Australia. See also radioactive iodine and Graves’ disease.

Sources

Checked 15 October 2026.

  1. Thyroid surgery (patient leaflet) — British Thyroid Foundation
  2. Thyroid disease: assessment and management (NG145), recommendations — National Institute for Health and Care Excellence
  3. Neo-Mercazole New Zealand data sheet, section 4.2 (preparation for surgery) — Medsafe (New Zealand)
  4. Hyperthyroidism (patient leaflet, updated October 2026) — British Thyroid Foundation
  5. Graves' hyperthyroidism: antithyroid drugs, surgery or radioiodine (Törring et al., 1996) — Journal of Clinical Endocrinology & Metabolism
  6. Comparative effectiveness of therapies for Graves' hyperthyroidism (Sundaresh et al., 2013) — Journal of Clinical Endocrinology & Metabolism