Hey, I found some stuff that are interesting.
So I tried figuring out what it is exactly that makes the oil dangerous. Apparently it contains eucalyptol also known as cineole which when ingested, causes problems.
"Eucalyptol has a toxicity (LD50) of 2.48 grams per kg (rat).[1] Ingestion in significant quantities is likely to cause headache and gastric distress, such as nausea and vomiting.[1] Because of its low viscosity, it may directly enter the lungs if swallowed, or if subsequently vomited. Once in the lungs, it is difficult to remove and can cause delirium, convulsions, severe injury or death.[1]"- Wikipedia
So from this, even though the danger comes from ingestion, it seems the bad stuff like unconsciousness and death comes from the substance entering the lungs since it's so volatile. I checked the cases of people that had eucalyptus oil poisoning, and in the report I came across a term; asphyxiation pneumonitis.
Aspiration pneumonia occurs when food or liquid is breathed into the airways or lungs, instead of being swallowed.
Which reaffirms that even when ingested and causes trouble to the digestive tracts, this chemical still finds it's says to the lungs to break more havoc. So maybe there's a way to bypass ingestion and vomiting and just inhale it into the lungs. Concentrated too, because this is a substance normally used in antiseptics and inhalants.
I saw a study where they tried inducing seizures in people that had no history of it, and they made use of eucalyptus oil by means of inhalation. Obviously they just used two to three drops with hot steaming water, I'm guessing to avoid fatality. But within 5min, people were having partial and tonic clonic seizures. Which I understand causes loss of consciousness and violent muscle contractions.
Maybe it'd lead to death if a large amount is inhaled or maybe it's easier to just ingest and die at a 50/50 chance