The word allergists is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 14
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (39 words)
aiglets, aigrets, airless, artless, gaiters, gassier, glister, grilles, gristle, largess, largest, ligases, ligates, literal, rallies, realist, relists, resails, retails, retills, rillets, sagiest, sailers, saltier, satires, serials, slaters, slatier, stagers, stagier, stellar, stiller, tallier, tallies, tigress, tillage, tillers, trellis, triages