The List
There are 161 5 letter words with I as the first letter. The highest scoring is IZZAT at 23 points in Scrabble. 50 carry three or more vowels, which makes them useful for dumping a vowel-clogged rack.
IAMBIIAMBSIBRIKICERSICHEDICHESICHORICIERICILYICINGICKERICKLEICONSICTALICTICICTUSIDANTIDEALIDEASIDEESIDENTIDIOMIDIOTIDLEDIDLERIDLESIDOLAIDOLSIDYLLIDYLSIFTARIGAPOIGGEDIGLOOIGLUSIHRAMIKANSIKATSIKONSILEACILEALILEUMILEUSILIACILIADILIALILIUMILLERILLTHIMAGEIMAGOIMAMSIMARIIMAUMIMBARIMBEDIMBUEIMIDEIMIDOIMIDSIMINEIMINOIMMEWIMMITIMMIXIMPEDIMPELIMPISIMPLYIMPOTIMSHIIMSHYINANEINAPTINARMINBOXINBYEINCLEINCOGINCURINCUSINCUTINDEWINDEXINDIAINDIEINDOLINDOWINDRIINDUEINEPTINERMINERTINFERINFIXINFOSINFRAINGANINGLEINGOTINIONINKEDINKERINKLEINLAYINLETINNEDINNERINNITINORBINPUTINRUNINSETINTELINTERINTILINTISINTRAINTROINULAINUREINURNINUSTINVARINWITIODICIODIDIODINIONICIOTASIPPONIRADEIRATEIRIDSIRINGIRKEDIROKOIRONEIRONSIRONYISBASISHESISLEDISLESISLETISNAEISSEIISSUEISTLEITCHYITEMSITHERIVIEDIVIESIVORYIXIASIXORAIXTLEIZARDIZARSIZZAT