Mum Emma McGinlay, from Renton in West Dunbartonshire, thought something was wrong when her daughter Ella kept spitting out the drink.
Then not long after, she started to throw up.
Emma told the Daily Record: "Before I had gone to work I tried to give her a cup of juice. I literally give her a wee tiny bit of juice. It is mostly water.
"She was drinking it but kept spitting it out. My husband texted me at work and said he had tried to give her some but she refused to take it.
"It wasn't like her. She drinks a lot and she's a really good eater."
The following day, Ella started being violently sick and this continued through the night and into Wednesday.
Emma continued: "I was really worried about her. She was really lethargic. She couldn't really sit up and then she started to have diarrhoea as well.
"I went across to the pharmacy and she was prescribed Dioralyte but she wouldn't even take that. I was racking my brain thinking about what she had eaten."
Emma went online to ask her Facebook friends what they thought might be wrong with her daughter – only to find that Tesco had actually recalled the squash because it mistakenly contained a foreign flavour additive that made it smell like garlic.
Emma said: "I checked my bottle and smelled it. It smelled like sewage. Neither my husband nor I had noticed it at the time because we give her so little of it but it was disgusting."
A Tesco spokeswoman said they had been in touch with Emma to apologise and provide details of how to obtain a refund.
She added: "We have investigated with our supplier complaints about Tesco no-added-sugar double concentrate apple and blackcurrant 750ml and 1.5l.
"A flavour additive, which is not part of the ingredients for this product, has been added in error. It is an approved additive and poses no food safety risk.
"However, it does have a strong odour, similar to garlic, which customers are likely to find unpleasant. We have withdrawn the product from sale.
"Only products bought since the New Year may be affected. They will have a best before date of October 2015.
"Any customers can return this product, open or unopened, to any Tesco store."
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