Antonyms of poisonous :
nontoxic, comestible, atoxic, eatable, unmalicious, edible, advantageous, favorable, helpful, profitable, serviceable, beneficent, good, invigorating, rejuvenating, useful, beneficial, healthful, life-giving, salutary, wholesome, curative, healthy, palliative, remedial, salubrious, benign, harmless, innocuous, inoffensive, nonfatal, nonlethal, nonpoisonous, nonvenomous.
Examples of usage:
It is as though some foul, poisonous gas is filling the air and filling His nostrils and steadily choking His gasping breath. "Quiet Talks about Jesus", S. D. Gordon.
It looks perfectly poisonous. "The Gem Collector", P. G. Wodehouse.
The unexpected sight of Sydney was like the sudden breaking out of sunshine through a bank of stormy cloud to the man whose whole mind had been filled for days with poisonous thoughts. "A Tar-Heel Baron", Mabell Shippie Clarke Pelton.