Poisons

Poisons are invariably detrimental to one or more species' well-being. While many drugs can induce similar effects, these may have other potentially beneficial uses whereas poisons are designed and/or administered with the primary intent to harm.

Cerberus turian poison
Cerberus developed a neurotoxin tailored to turians that saw usage during their failed takeover of the Citadel. General Korilius was stabbed with a poisoned blade while defending civilians, rendering him comatose with the doctors at Huerta Memorial Hospital unable to identify the toxin.

Schematics for the poison can be found at an ex-Cerberus facility on Gellix. A former Alliance researcher has data on a similar toxin that was developed in case of a war with Palaven, and is amenable to selling it at the Spectre Requisitions office if the Cerberus schematics weren't found on Gellix. Either can be used in the synthesis of an antidote that cures General Korilius.

Drell subcutaneous oils
The drell secrete a toxic compound that other species find highly intoxicating and even hallucinogenic. This is why they generally do not wear environmental suits; even they would suffer its effects after prolonged exposure.

Element zero
Exposure to significant amounts of eezo either grants biotic ability to the victim (and offspring, if pregnant) or promotes the growth of cancerous tumors. Overexposure tends to shift the balance to the latter.

Final Jest
A batarian poison that turns blood to lighter fluid and uses the brain's electrochemical pain response to set the victim on fire from the inside. Victims end up with big fat orange blisters that may be blue if the venom sacs aren't too fresh, but the observations are moot since they explode quickly anyway. Available on Khar'shan.

Mother's Milk
A caustic liquid that dissolves the victim's throat mid-swallow. Gives victims a suppurating "scarf" of red. Another batarian poison available on Khar'shan.

Pauper's Pleasure
A batarian poison available on Khar'shan. Pauper's Pleasure causes purple hives in the victim's skin before their saliva boils and they slowly braise in their own bodily fluids.

Polonium
This element's radioactivity is used to coat certain types of ammunition for extra damage against organic targets.

Ruthenium dichloride
This compound is most often used together in commercial canning, preserving, bottling, and labeling, though it is toxic to asari, humans, and salarians. It can be found in Horosk bottles.