Sodium Iodide I 131 (Therapeutic)

Side Effects of This Medicine

Studies have not shown that sodium iodide I 131 increases the chance of cancer or other long-term problems. When used to treat an overactive thyroid gland, sodium iodide I 131 may cause the patient to have an underactive thyroid gland after treatment. The thyroid gland may become underactive even several years after treatment for hyperthyroidism. Before receiving this medicine, be sure you have discussed its use with your doctor.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

When this medicine is used in very small doses to help study the function of the gland, side effects are rare. However, check with your doctor as soon as possible if any of the following side effects occur after treatment for overactive thyroid or cancer of the thyroid:

After treatment of overactive thyroid

Symptoms of an underactive thyroid

Changes in menstrual periods; clumsiness; coldness; drowsiness; dry, puffy skin; headache; listlessness; muscle aches; thinning of hair (temporary) - may occur 2 to 3 months after treatment; unusual tiredness or weakness; weight gain

Rare

After treatment of overactive thyroid

Excessive sweating; fast heartbeat; fever; palpitations; unusual irritability; unusual tiredness

After treatment of cancer of the thyroid

Black, tarry stools; blood in urine or stools; cough or hoarseness; fever or chills; lower back or side pain; painful or difficult urination; pinpoint red spots on skin; unusual bleeding or bruising

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

Less common

After treatment of overactive thyroid or cancer of the thyroid

Neck tenderness or swelling; sore throat

After treatment of cancer of the thyroid

Loss of taste (temporary); nausea and vomiting (temporary); tenderness of salivary glands

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.