Hi Dear, Welcome to HCM. Understanding your concern. Thanks for your query. Well your are wondering if Levothyroxine cause hard bumps on back of tongue . The symptoms you mention in query are pointing towards enlarged papillae . They become enlarged when they get irritated or there is some trigger factor that disturb then physiologically . Levothyroxine can also cause throat discomfort , consult doctor who prescribed it , who may alter the dose or prescribe substitute . There are certain trigger factors responsible for there enlargement like hormonal changes , stress , hot and spicy food , poor oral hygiene or acidic food . They usually get normal without any treatment within few days . I would suggest you to :- - Do warm saline rinses several times a day . - Avoid hot and spice food or acidic food . - Maintain proper oral hygiene by brushing and flossing teeth twice a day . - Do mouthwash rinses (listrine ) twice a day . I condition doesn t get better in a week then consult oral pathologist for proper examination and to rule out other conditions like canker sores oral herpes. Doctor may prescribe antibiotics (amoxicillin) or anti allergic drug like zyrtec or sucralfate . Doctor may also refer you to ENT specialist . Hope your concern has been resolved. Best Wishes, Dr. Harry Maheshwari