Gandhi was discharged around 1.30 a.m. Tuesday after undergoing several tests, All India Institute of Medical Sciences director R.C. Deka told reporters here.
He added that the Congress president was suffering from fever and headache for which she took medicines. "The medicines did not suit her due to which she suffered uneasiness in the Lok Sabha," Deka said, adding that Gandhi's test results were found normal after which she was discharged from the hospital.
Gandhi, 66, earlier took part in the debate in the Lok Sabha on her pet food security bill which was later passed unanimously. Her speech was heard in silence by the house.
Later, she complained of uneasiness and looked shaken as she left the house.
She appeared to stumble as she walked down the parliament steps. Gandhi quickly held central minister Kumari Selja's left hand and recovered her poise.
Her son Rahul Gandhi and Selja accompanied her in the car to the AIIMS. The Congress president's daughter Priyanka Gandhi joined them at the hospital.
Later, hordes of senior Congress leaders including Prime Minister Manmohan Singh, Delhi Chief Minister Sheila Dikshit and some central ministers visited Gandhi at the hospital.
"According to our information, there is nothing to worry, some medicine did not suit her... She is fine and has appealed to everyone to leave. There is nothing to worry," Congress leader Janardan Dwivedi told the people gathered there.
Senior Bharatiya Janata Party leader Sushma Swaraj wished Gandhi a speedy recovery through a message on social networking site Twitter.