Radioiodine Therapy: A Step-by-Step Patient Guide from Treatment to Recovery

February 4, 2026

Lt Col (Dr) Anand YNI
DRM, DNB (Nuclear Medicine), MD (Radio diagnosis) Senior Consultant & Head of the Department

Seeking specialised medical care for a health issue is never enjoyable. But knowledge can provide a sense of control and reassurance. Radioiodine therapy (RAI therapy) is commonly used as a long-standing treatment for various thyroid disorders. It employs radioactive iodine to target specific thyroid cells.

This guide details the full radioiodine therapy experience from preparation to physical recovery, making you feel informed and supported every step of the way.

How Does Radioiodine Therapy Work Within the Body?

To comprehend what radioiodine ablation therapy is, we need to understand the special link between iodine and thyroid glands. … the thyroid, the only part of our body that absorbs iodine, contrary to most other substances.

You receive radioactive iodine-131 as a capsule or liquid to swallow. The radioactive isotope becomes concentrated directly in the thyroid gland because the latter has a natural affinity for iodine.

The released radiation penetrates only a few millimeters, enough to obliterate overactive or abnormal thyroid cells: it leaves surrounding tissue mostly untouched, including the parathyroid glands and vocal cords. This directed treatment is the basis of nuclear medicine.

The treated cells shrink or die off over time; it takes several months for the full effect, so hormone levels finally do level out, and relapses are less likely after surgery or extended medication.

Key terms:

• Radioiodine: A radioactive form of iodine (usually I-131) used to treat thyroid disorders.

• Isotope: Variants of the same element with different numbers of neutrons.

• Localised radiation: Radiation confined to a small, targeted area.

Conditions Treated Using RAI Therapy 

RAI treatment has been used for hyperthyroidism, where the thyroid gland produces too much hormone. Symptoms could include rapid heartbeat, weight loss, sweating, and anxiety. Research has demonstrated that the radioiodine treatment of hyperthyroidism is followed by a single dose as long-lasting remission in more than 85% of patients.

Graves’ disease is an autoimmune condition in which the immune system triggers the thyroid to produce more hormones. Radioiodine therapy for Graves’ disease is often recommended when anti-thyroid medications are ineffective or cause side effects.

Radioiodine therapy is a common treatment for thyroid cancer as well. If the thyroid gland is removed surgically (thyroidectomy), radioiodine ablation therapy may be performed to eliminate any microscopic thyroid tissue or cancer cells that are left.

Key terms:

• Hyperthyroidism: Overproduction of thyroid hormones.

• Thyroidectomy: Surgical removal of part or all of the thyroid gland.

Before Treatment: Preparing for the Radioiodine Therapy Procedure 

The thyroid absorbs radioactive iodine better with good preparation.

Patients are generally instructed to be on a low-iodine diet for 1–2 weeks before treatment. This includes avoiding:

Iodised salt

Seafood

Dairy products

Certain processed foods

A few medicines, especially anti-thyroid drugs, are discontinued 5–7 days before treatment to enhance uptake.

In the case of thyroid cancer patients, doctors can inject recombinant human TSH to increase levels of the thyroid-stimulating hormone and make the treatment more conducive.

During & After Treatment: What to Expect

• The process of radioiodine therapy in itself is very easy and pain-free. The patient ingests a capsule or liquid that contains radioactive iodine.
• Most people go home the same day, but higher doses that are given with cancer treatment may require a short hospital stay.
• Safety precautions: Because tiny amounts of radioactivity come out in the urine for a few days, it’s important to:
• Avoid close contact for 3–7 days. Children, pregnant women
• Do not share towels, beddings, or utensils.
• Do this by drinking plenty of liquids to help clear your body of the extra iodine from the body.

Side effects are usually mild and temporary and may include neck discomfort, dry mouth, or temporary changes in taste.

Key terms:

• Radiation safety: Measures to protect others from exposure.

• Isolation: Maintaining distance to minimise radiation transfer.

Recovery Details After Radioiodine Ablation Therapy

Recovery is gradual. With most women, her hormone levels will start to shift within just a few weeks, but the full benefit may not be complete until three to six months.

Ongoing blood tests are needed to check levels of thyroid hormone and modify treatment as necessary.

About 90% of patients who are treated for hyperthyroidism will finally develop hypothyroidism (a lower thyroid hormone), which is the purpose of giving this treatment. It is easily treated with a couple of thyroid hormone replacement pills every day and is regarded as a very predictable and manageable factor. In any case, of the two, hypothyroidism is more preferable than hyperthyroidism.

Key terms:

• Hypothyroidism: Insufficient production of thyroid hormones.

• Hormone replacement therapy: Daily medication to maintain normal hormone levels.

Key Benefits of Radioiodine Therapy

Radioiodine therapy offers several advantages:

• Non-surgical and painless

• No surgical scars or anaesthesia risks

• Highly targeted treatment

• Cost-effective

• High long-term success rate

• Permanent solution for medication-resistant hyperthyroidism

Relapse rates after RAI therapy are generally below 10%, significantly lower than long-term drug therapy alone.

Trusting Nanjappa Hospital for Your Care

Cutting-edge technology and compassionate care are crucial to the successful treatment of the thyroid. At the Nanjappa Life Care Super-speciality Hospital, we realize that for each patient, his experience of RAI is different.

The Nuclear Medicine section of our institution includes the necessary updated technical equipment in order to conduct each radioiodine therapy with the best security and accuracy.

From radioiodine therapy for hyperthyroidism to radioiodine ablation therapy after thyroid surgery and everything in between, our experts stay at your side before and after treatment.

At Nanjappa Hospital, we prioritise clear communication, patient comfort, and long-term health, helping you regain balance, confidence, and quality of life through expert care.