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.
Check with your doctor as soon as possible if any of the following side effects occur:After treatment of overactive thyroidSymptoms of an underactive thyroid
- Changes in menstrual periods
- Dry, puffy skin
- Muscle aches
- Thinning of hair (temporary)—may occur 2 to 3 months after treatment
- Unusual tiredness or weakness
- Weight gain
- Excessive sweating
- Fast heartbeat
- Unusual irritability
- Unusual tiredness
- 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
Some 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. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:Less commonAfter treatment of overactive thyroid or cancer of the thyroid
- Neck tenderness or swelling
- Sore throat
- Loss of taste (temporary)
- Nausea and vomiting (temporary)
- Tenderness of salivary glands
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.