Two alleged poisonings occurred in Dunedin on August 16, while the remaining charges span five days in Auckland.
As well as "pharmacy-only eye-drop medication", court documents specified the substances the defendant allegedly administered to her son were sertraline, tetrahydrozoline, naphazoline, pheniramine and antazoline.
Associate Prof Dr Ivan Sammut, of the University of Otago department of pharmacology and toxicology, said sertraline was used to combat depression while the others were antihistamines, non-inflammatories or decongestants usually present in eye drops and nasal sprays.
Such substances were not prescribed to toddlers and depending on dosage, they could have catastrophic consequences.
The defendant allegedly combined the depression medication with the others, something Dr Sammut said could be particularly dangerous.
An immediate increase in heart rate would be followed by a swift decline and "a massive drop in core temperature".
Eye drops could likewise create problems.
"A child with a small body volume, there's a very good chance the drops will penetrate faster into the circulation because the tissues aren't as well formed," Dr Sammut said.
Because the majority of the alleged offending occurred in Auckland, the matter was transferred from Dunedin to the Auckland District Court.
Two Auckland-based detectives were in court to see the defendant's first appearance this week.
She will appear again next month and, ultimately, the matter may be transferred to the High Court.