 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  of the neck (goiter). This drug may cause your skin to be more sensitive to the sun. With long-term treatment, you may rarely develop blue-gray color of the skin. This effect is not harmful and color may return to normal after the drug is stopped. To help prevent skin effects, limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness. This drug may rarely cause vision changes. Very rarely, cases of permanent blindness have been reported. Tell your doctor right away if you develop any vision changes (such as seeing halos or blurred vision). A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800 </s>