The best replacement for toxin is poison.

The best alternatives to toxin are rated as following:
★★★★★  poison
★★★  carnage
★★★  toxicant
★★★  venom
★★  toxoid
★  anti venom
★  agent venom
★  pathogen
  c-diff antigen
  antigen
  toxic

Your alternative for toxin is not listed? Suggest!
Speaking about toxin, one probably shouldn't forget about negative c diff antigen.

Other search terms related to toxin and their ratings are:
★★★★★ negative c diff antigen
★★ e coli
You have in mind a companion for toxin and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of toxin in all years. Click on graph for more.
toxin
poison
carnage