A warrant for Mary Ellen Cannon was signed Monday, Oakland County Chief Deputy Prosecutor Deborah Carley said. Cannon was expected to face five felony counts, including attempted murder and poisoning.
Police said the motive was unclear.
If convicted, the 46-year-old suburban Detroit woman could be sentenced to up to life in prison.
Carley told the Detroit Free Press that Cannon tried to kill her 57-year-old husband, Richard Shaw, and 13-year-old son, Ian Shaw, on Oct. 26. Authorities say Cannon purchased one chocolate and one strawberry milkshake from a McDonald's two days earlier, put them in a freezer and later gave them to her husband and son.
Carley said Richard Shaw collapsed and Ian Shaw later became ill. The boy was hospitalized for three days, and the husband, who went into a coma but later recovered, was hospitalized for 11 days.
Authorities said Cannon apparently ground up her own medication for the milkshakes.
Toxicology reports indicated that lethal doses of prescription medications prescribed for sleep disorders and panic attacks, regulating blood pressure and easing pain were found in the milkshakes.
The initial report was that the husband had the flu and was unable to wake up, The Daily Oakland Press reported, but paramedics doubted the wife's explanation as they transported the two people to a hospital.
"As the story progressed, and they took the history, they became a little suspicious," Troy police Lt. Gerry Scherlinck said.
The wife's lack of concern made paramedics suspicious. The father had passed out while walking the dog and had to be carried in by a neighbor and the son. Scherlinck said the wife left her husband in a recliner for 24 hours, and he never woke up.
The neighbor wanted to call for help, believing the man had suffered a heart attack, but the wife apparently said that she had seen plenty of heart attacks and that her husband had suffered from seizures, The Daily Oakland Press reported. Both statements turned out to be false, police said.
Cannon was being held at the Oakland County Jail.