Don’t make your girlfriend mad.

A prominent Houston oncologist is accused of attempting to poison a colleague whom she was dating by lacing his coffee with a chemical used in antifreeze.

Dr. Ana Maria Gonzalez-Angulo, 42, was charged with aggravated assault of a family member after she allegedly put ethylene glycol, often found in antifreeze, into a cup of coffee and served it to Dr. George Blumenschein at her Houston home in January, according to ABC News.

When Blumenschein, who reportedly preferred his coffee black, asked Gonzalez-Angulo why the coffee tasted sweet, she told him she put Splenda in it. When he asked her for a fresh cup, she allegedly told him to finish the coffee she gave him before serving him another cup, which tasted just as sweet.

Blumenschein experienced slurred speech, poor balance and loss of fine motor skills approximately four hours after drinking the poisoned coffee. He was hospitalized after 16 hours, and doctors determined he was experiencing central nervous system depression, cardiopulmonary complications and renal failure.

Tests revealed that the amount of ethylene glycol he consumed could have been fatal, according to ABC News. Blumenschein had to undergo dialysis and is currently in a doctor’s care.

Gonzalez-Angulo and Blumenschein both worked as oncologists at The University of Texas MD Anderson Cancer Center in Houston.

Gonzalez-Angulo is on paid administrative leave from the hospital, a hospital spokeswoman told KTRK-TV.

She was arrested in Harris County on May 29 and booked into the Harris County Jail on May 30, court records stated. Her bond was set at $50,000.