Layla Myles, 30, said she feared her 22-month-old son Riley could have been blinded for life after the accident at their home in Ashford, Kent.
Riley bit into the Vanish Powershot Gel Cap causing the liquid inside to spray into his face.
The little boy's eye swelled shut and the detergent also got into his mouth and dripped on his stomach.
Layla, 30, said: "I heard him scream. The chemicals were burning him. I was terrified he wouldn't be able to see properly."
Riley was in hospital for four days and put on a drip. Doctors do not believe he suffered internal damage.
Layla said: "His eye looks a lot better but he's going to need his sight monitored every three months.
I want to warn parents to keep the capsules locked away in a cupboard. We had left ours on the side and somehow Riley managed to climb up.
"The capsules come in a child-proof plastic box, but Riley still got into it."
Earlier this month, we revealed on Parentdish how a Glasgow hospital had treated FIVE youngsters under the age of two after biting into similar capsules.
Philip Malpass, director general of the UK Cleaning Products Association, said: "The industry should introduce child-frustrating closures, safe-use icons and opaque packaging so children cannot see inside.
"But the best tactic is for parents to keep the boxes and capsules out of reach of children."