The Collaborative International Dictionary of English v.0.48:

Fluster \Flus"ter\, v. t. [imp. & p. p. Flustered; p. pr. &
   vb. n. Flustering.] [Cf. Icel. flaustra to be flustered,
   flaustr a fluster.]
   To make hot and rosy, as with drinking; to heat; hence, to
   throw into agitation and confusion; to confuse; to muddle.
   [1913 Webster]

         His habit or flustering himself daily with claret.
                                                  --Macaulay.
   [1913 Webster]

WordNet (r) 3.0 (2006):

flustered
    adj 1: thrown into a state of agitated confusion; (`rattled' is
           an informal term) [syn: flustered, hot and
           bothered(p), perturbed, rattled]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "flustered":
   addled, agitated, balled-up, beery, bemused, besotted, blind drunk,
   bothered, chaotic, confused, crapulent, crapulous, discomposed,
   disconcerted, disordered, disorganized, disquieted, disturbed,
   dizzy, drenched, drunk, drunken, embarrassed, excited, far-gone,
   feverish, fidgety, flurried, fluttered, fou, full, fussed, gay,
   giddy, glorious, happy, in a jumble, in a pother, in a pucker,
   in a stew, in a sweat, in a swivet, in a tizzy, in liquor,
   inebriate, inebriated, inebrious, intoxicated, jittery, jolly,
   jumbled, jumpy, maudlin, mellow, merry, mixed-up, muddled, nappy,
   nervous, nervy, perplexed, perturbed, put-out, rattled, reeling,
   restless, ruffled, shaken, shaken up, shikker, shook, shuffled,
   sodden, sotted, stirred up, tiddly, tipsy, troubled, troublous,
   turbulent, under the influence, uneasy, unpeaceful, unquiet,
   unsettled, upset