Vandana was found in an unconscious state by a family member at her home in Welcome area in east Delhi Friday evening, police said, adding that she was depressed.
She telephoned her parents after eating the poison and said that she was going to die, police said.
The teacher at a municipal corporation school was admitted to Lal Bahadur Shastri Hospital where she died Saturday, police said.
In January, Vandana married Manish, who is in a private job, a police officer said.
Manish was arrested Sunday following a magisterial inquiry, the officer added.