Evan Waters screamed after he was nipped on the finger as he ate the fruit at home.
His right hand swelled “like a balloon” and mum Kellie Bright rushed him to hospital, where he was treated by doctors for two days.
Kellie, 29, said: “It was terrifying. The spider had scurried away when we heard Evan screaming.
“We got to the hospital and doctors said it was a spider bite. We don’t know if it was a tarantula, black widow or huntsman spider.”
Kellie said Evan’s hand was paralysed for two days. He is now home but his mum said: “Evan’s skin has blisters, his temperature’s still been high and his heart rate was up.”
Worryingly for the family, the spider could still be in their home in Bishop Auckland, Co Durham.
Mum-of-four Kellie said: “My older children were terrified to go back into the house. I’ve been told to contact Environmental Health.”
An Aldi spokesman apologised and said: “We are investigating with our suppliers.”