The word allergenic 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: 18
Highest Scoring Words With Friends™ Play In The Letters allergenic
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Seven Letter Word Alert: (25 words)
aircell, aligner, alleger, angelic, calling, celling, cleaner, clinger, elegaic, elegiac, enlarge, general, generic, glacier, glancer, gleaner, gracile, learing, leering, lineage, realign, reclang, reclean, recline, reeling