A patient with hyperthyroidism presents for dental care. Which medication should be avoided or used with extreme caution?

Correct answer: C. Epinephrine (in local anesthetic)

• A. Sodium fluoride has no specific interaction with hyperthyroidism.
• B. Acetaminophen is generally safe in hyperthyroidism (though the liver may be mildly affected, standard doses are not contraindicated).
• C. Correct. In hyperthyroidism, the patient already has an elevated sympathetic tone (tachycardia, hypertension, heat intolerance). Adding epinephrine (a sympathomimetic) can precipitate a thyrotoxic crisis — a life-threatening surge of thyroid hormone causing extreme tachycardia, hypertension, and cardiovascular instability. Epinephrine in local anesthetics should be avoided or strictly limited in uncontrolled hyperthyroidism.
• D. Amoxicillin has no specific interaction with hyperthyroidism.