Acute poisoning caused by oral or inhalation of large amounts of cyanide or use of cyanide-containing foods (such as cassava, barley) without proper treatment. The severe case was immediately comatose, and the breathing stopped within 2-3 minutes. The lighter cases first had fainting, headache, and vomiting, and later had palpitations, dyspnea, convulsions, and coma.
One gram of cyanide can kill about 500 people and can cause death if used in large doses for a few seconds. Known as the lightning poison.
The math genius Turing died of cyanosis, and apple seeds contain cyanide. When you have 150 compressed apple seeds, you will have seizures and cardiac arrest in a few seconds.