Gandhi, 66, was taken to hospital from the national parliament, where she had earlier urged lawmakers to pass landmark legislation offering subsidised food to millions of India’s poor.
“She complained of a headache and she had a cough,” said the doctor who did not want to be named because he is not authorised to speak to the media.
“We checked all her parameters. Once the team of doctors was convinced that she was all right, she was discharged,” he told AFP, adding that she was released about 3:00 am.
Late on Monday, parliament passed the Food Security Bill, which has been championed by the Congress leader, who included it as a manifesto pledge for the elections in 2009.
The bill — seen as a vote-winner by the ruling Congress party ahead of national polls next year — was adopted in the lower house after a nine-hour debate.
The scheme will provide food grain to nearly 70 percent of the population, or 800 million people, for as little as one rupee per kilo.
In a rare speech in parliament, Gandhi had told MPs to send a message to the world that India was ready to eradicate malnutrition, which Prime Minister Manmohan Singh has described as a “national shame”.
Television footage showed Gandhi leaving parliament on Monday evening, escorted by her son, to go to hospital.
“She was feeling uneasy in the parliament,” Congress party general secretary Janardan Dwivedi told reporters outside AIIMS hospital.
“She was rushed here to AIIMS. She has gone back home, she is all right and her medical check-up has been completed… there is nothing to worry. She is completely fine,” he added.
In 2011, Gandhi travelled to the United States for surgery for an undisclosed illness, reportedly cancer. Her health and private life are closely guarded by her advisors.