I'm due to have a thyroid scan in 3 days. Yesterday, I took two 25 mg antihistamine pills. Will this affect the results?
No, it should not.
The half life of most antihistamines should be less than 24 hrs and should be out of the system by then.
I would check with the radiology center to confirm their policy. I would also avoid any more antihistamines until the time of testing.
INFLAMMATION OF THE THYROID