Smelling a rat: Kenyan marathon runner banned after testing positive for rodent poison
The Athletics Integrity Unit (AIU), which has banned the runner from competition until November 14, also stripped Kirwa of his second place at the 2018 Singapore Marathon.
The 23-year-old insists that the banned substance accidentally entered his body through herbal medicines which he consumed for therapeutic reasons.
The AIU said the athlete violated anti-doping ruling as "he did not exercise utmost caution to ensure that he did not use a prohibited substance."
Strychnine is a strong performance enhancement stimulant which helps athletes to increase running stamina and boost endurance over long distances.
However, the banned drug has serious side effects, including restlessness and muscle spasms.
Kirwa is the brother of 2016 Olympic women’s marathon silver medalist Eunice Kirwa, who represented Bahrain at the Games. She was also provisionally suspended last month after failing a drug test.