It seems that Mary had a healthy instinct protecting her from becoming addicted to opium.
This is remarkable, noting that Thomas Syedenham (1624–1689), who was considered the “English Hippocrates” recommended opium to treat pain, sleeplessness, and diarrhea, asserting that:
"Among the remedies which it has pleased Almighty God to give to man to relieve his sufferings, none is so universal and so efficacious as opium."
Being a medical observation, this positive view on opium was maintained and manipulated by rulers in China to control their population, up until the 16th century, and from the 18th century the British traded and smuggled opium into China, to make money and to control the Chinese rulers, by trying to reduce them all to helpless opium addicts.
Interestingly, George Orwell, who once likened Britain to a wealthy family that maintains a guilty silence about the sources of its wealth, is closely linked by family ties to this history. Bon as Eric Blair, George's father, Richard W Blair, managed the production of opium on plantations near the Indian-Nepalese border, as a civil servant, and also supervised the export to China.
Unfortunately for Orwell, the Blair family fortune had been largely squandered by the time he was born. That might explain why he switched sides, and tried in his novel "1984" to alert his fellow-humans to the conspiracy of the rich and powerful.