At least 24 children fell ill on Friday after eating the mid-day meal at a government school in Bihar's Khagaria district, officials said.
Their condition is stable.
The children complained of uneasiness after consuming the meal at Parbatta Middle School, and were admitted to the local primary health centre, a district official said.
"All the children are out of danger," he said. "All of them, except four, were discharged after preliminary treatment at the hospital," he added.
Police have collected samples of the meal for forensic examination.
According to officials, some children said a lizard was found in the mid-day meal served to them.
However, the doctors who examined the children did not find any sign of poison in their bodies.
Sixteen million students in 72,000 schools across Bihar get food under the mid-day meal scheme.