The word allergist 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: 13
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (25 words)
aiglets, aigrets, gaiters, glister, grilles, gristle, largest, ligates, literal, rallies, realist, retails, retills, rillets, saltier, slatier, stagier, stellar, stiller, tallier, tallies, tillage, tillers, trellis, triages