Mary Aldecoa started feeling sick every day after lunch.
"Every afternoon I started getting a really bad pain in my stomach, and I started feeling light-headed and dizzy, and that would be followed by a really bad headache," she said.
Little did she know, one of her algebra students at Fowlerville High School was making her sick.
"The student told them that he did indeed put Visine in my coffee cup," said Aldecoa.
If ingested, Visine can cause a drop in blood pressure, seizures and even a coma. Aldecoa said she doesn't believe the student was acting maliciously.
"If I had been really seriously injured or died, this poor kid's life would be ruined over what was probably just a harmless prank," she said.
She said there was a small window where someone could poison her coffee cup -- in between classes when teachers are monitoring the hallways or right after lunch before classes resumed.
"It's disturbing to have that happen, gets so sick and not find out until a week later why you were so sick," she said. "And then it's like being victimized all over again."
A teacher for 24 years, Aldecoa said she won't leave her cup of coffee at her desk again.
"I won't have a coffee cup in the classroom, I just won't," she said.
The student responsible was found out after a rumor started going around the school. Authorities investigated and the student was suspended for a year.
Aldecoa agrees with the suspension but still mentioned she hopes he receives schooling during that time.