Strychnine. Vial of strychnine used for forensic research. Strychnine is a poison that is used in rat poisons and other pesticides. It can be fatal to humans, and there have been cases of accidental as well as deliberate poisoning. Forensic analysis is used to determine whether a particular case of poisoning involves strychnine. Some tests, such as spectroscopic analysis, require a sample of pure strychnine to compare with the suspected poison. Poisoning is usually by ingestion, but can also be by inhaling the powder. Symptoms include muscle spasms that can prevent breathing and cause death. Amounts of over 30 milligrams (mg) are sufficient to kill.