A 53-year-old woman has been arrested after a baby drank liquid, thought to be bleach, aparently given to him by a stranger.
The baby was in a stable condition in hospital after he swallowed the contents of the bottle at McDonald's in Eltham, southeast London.
The toddler was with his mother and grandmother in McDonald's when the incident took place around 12.40pm on Thursday.
Officers recovered the bottle and tests were being carried out to find out what it contained. The Metropolitan Police alerted the public to the danger via Twitter that afternoon.
Police believe the baby was the only victim.
The woman was arrested in Deptford on Friday morning and was being questioned at a south London police station.