Yes, so very many poisons. The reason MHO settled on cyanide was this:
At lower doses, loss of consciousness may be preceded by general weakness, dizziness,
headaches,
vertigo,
confusion, and perceived difficulty in breathing. At the first stages of unconsciousness, breathing is often sufficient or even rapid, although the state of the person progresses towards a deep coma, sometimes accompanied by
pulmonary edema, and finally cardiac arrest. A cherry red skin color that changes to dark may be present as the result of increased venous
hemoglobin oxygen saturation. A fatal dose for humans can be as low as 1.5 mg/kg body weight.
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Cyanide poisoning - Wikipedia
Fits with AC, and TD with her pink foam. Also, difficult to trace.