Since it is currently relevant, to myself at least, Did you Know...
The Queen of Poisoners was a real queen, her name, Catherine de Medici. She was fond of brewing her own potions and then testing them on indigent subjects who were given royal 'favours'. She then recorded their deaths in detail. One of her favorite means of dispatch was diamond dust.
Diamond, when powdered & swallowed causes death not because it is poisonous, but the pieces of diamond which are sharper like glass pieces (in fact knives with diamond edges are used to cut glass ) cut the inner walls of the small intestine causing excessive internal bleeding & death is due to loss of blood.
The french euphemism for poison in 17th century was 'Poudre de succession[ (Inheritance powder)
White arsenic trioxide As2O3, was a highly favored poison, for it is odorless, easily incorporated into food and drink. Symptoms of arsenic poisoning begin with headaches, confusion, explosive diarrhea, implosive diarrhea, and drowsiness. As the poisoning develops, convulsions and changes in fingernail pigmentation called leukonychia may occur. When the poisoning becomes acute, symptoms may include diarrhea, vomiting, blood in the urine, cramping muscles, hair loss, stomach pain, and more convulsions. The organs of the body that are usually affected by arsenic poisoning are the lungs, skin, kidneys, and liver. The final result of arsenic poisoning is coma to death
Signora Toffana provided a popular service for the ladies in Naples at the end of the 17th century. She sold them 'Aqua Toffana', an interesting and expensive liquid they were instructed never to ingest themselves. It was sold as a complexion aide. Ladies were told to apply it to their faces, necks and breasts before meeting their husbands. Signora Toffana was executed in 1709 for the murder of 600 men. The 600 rich widows presumably walked free.
In the 1680s, the Affair of the Poisons scandal broke in Paris. A former midwife turned witch was hawking potions to the nobility and in some cases, more lethal wares as well. When it was discovered that the king's mistress was feeding him one of the witch's love philtres, the scandal broke. The witches name was Madame Voisin.
The Vish Kanjas were apparently reared from infancy on minute doses of strychnine. By the time they were in their teens their tolerance would have been massive and contact with their body fluids, fatal. So that their kiss could kill. It produces some of the most dramatic and painful symptoms of any known toxic reaction. For this reason, strychnine poisoning is often used in literature and film. A severe nausea is seen, which may include vomiting due to the bitter taste, convulsions affect all the muscles growing quicker and more intense.The face becomes cyanosed, with dilated pupils and prominent eye balls. The mouth may also froth. These symptoms are all due to spasms of the facial muscles. The body may be seen arch-shapes. The person is conscious and the mind is clear until death. There is an immense reflex excitability. Even a small stimulus like light, noise or movement of the body may throw it into a spate of convulsions. Death usually occurs due to asphyxia as respiration is affected by muscle spasm.