I accidentally took 500mg more of my 100mg levothyroxine. i mistook them for my prednisolone as i have colitis. i tried vomit them up. am i in danger?

Unlikely but . . .: If you missed your Prednisolone dose, then your colitis might flare. We rarely recommend inducing someone to vomit out of fear of more damage on way back up as well as aspiration (breathing food/liquids/chemicals etc into lungs). Half-life of Levothyroxine is 6-7d so if you took 4 extra pills, ask your GP about skipping next 4, then restart on schedule. Watch out for symptoms of hyperthyroidism.