Little Sonny Rees drank the 40 percent proof spirit – which he thought was fruit juice - at his second birthday party in Frankie & Benny's Swansea branch.
He started pulling strange faces and
wriggling in his chair - then his parents smelt the whiff of booze in his glass.
Sonny was taken to A&E where he was kept under observation.
The toddler was recovering at home today while the restaurant carried out an investigation into the mix-up.
Sonny's anxious mum Nina Rees, 34, said: "We went to the restaurant just after midday, and I had ordered him lime juice and water, his favourite.
"The drinks arrived and I was encouraging him to take sips through a straw because he was eating salty things.
"We had finished our first course when we noticed he was pulling a face as he was drinking.
"I took it from him and took a sip myself.
"It was whisky, I would say a double.
As soon as I sipped it I had the slight burny feeling in my throat and warming in my chest.
"Sonny had taken about ten sips - he was obviously intoxicated.
"I immediately went into a panic and
a rage - I was crying my eyes out."
Teacher Nina complained to the manageress who refused to believe her until she took a sip herself.
Nina said: "The first reaction of the
staff was awful.
"They said it couldn't have happened and just went and got him some water and walked off. They more or less dismissed me.
"I called NHS direct who told me to
take him straight to A&E."
Nina, the head of IT at a high school, later found out that a stag-do was going on in the bar and staff mixed
up Sonny's drink with a whisky and water ordered by one of the male revellers.
The family even took birthday snaps of Sonny with his drink - not realising it was a drop of the hard stuff.
Sonny was asleep by the time he arrived at Morriston Hospital in Swansea where staff monitored his vital signs.
He was later given the all-clear by medics and allowed home.
The restaurant gave the family a 50 per cent discount on their bill and called Nina and her police IT consultant husband Howell to apologise.
A Frankie and Benny's spokesman said: "The company is incredibly sorry for what happened.
"It was a human error and we are putting measures in place to ensure it never happens again."