Susan Sheridan had heard of ChatGPT but had never used it, so the first question she asked the artificial intelligence chatbot was a bit garbled: “Facial droop, facial pain and dental work.”

She had turned to ChatGPT in a moment of desperation. The right side of her face was sagging, she tripped over words as she spoke and her head hurt so much that she couldn’t rest her head on the pillow.

A day earlier, when her husband first noticed the drooping, the couple drove three hours to an emergency room, only for the doctor to send her home after labeling her symptoms as benign.

ChatGPT disagreed. One potential explanation for her symptoms, the chatbot told her, was Bell’s palsy, which needed urgent treatment to avoid lasting damage.

She made another trip to the emergency room, where a doctor confirmed the chatbot’s suspicions and gave her steroids and antivirals. As a result, she was mostly cured.

“I don’t want to replace doctors — I believe in the doctor-patient relationship, I believe in the health care system,” said Ms. Sheridan, 64, co-founder of a patient safety advocacy organization.