Jemima Strain, from Dudley in the West Midlands, said her son picked one of the tablets up and popped it, but she had no idea how “awful” the contents were.
“Please make sure that your children never touch these,” she wrote on Tuesday 18 April alongside a photo of Fairy tablets. “The liquid went in his eyes.
“After washing them out as much as possible he was still clearly in a lot of discomfort and pain. My husband rang NHS direct who told us to get him to A&E immediately.”
Strain explained that on arriving at A&E, she had a team of nurses trying to get her son to open his eyes to neutralise the liquid with saline fluid.
The family were then immediately taken to the eye specialist clinic at Birmingham City hospital as they found burns in his eyes.
Strain explained: “He was traumatised as was I. The consultants said if we had not washed his eyes out, my son would have suffered from further burns to his eyes.
“Please let everyone you know hear of this and share it as a warning.”
She added: “I thought we were doing great parenting letting our children help with the washing.
“It’s an awful advertising gimmick making them look like fun squidgy pouches. Even I’ve been tempted to give it a squish. The manufacturers need to look at child proofing the boxes and take this much more seriously.”
Strain encouraged parents not to allow their children to help with the washing.
“We were fortunate... we acted fast and he was only blind for three days and with drops started to open his eyes and now has full sight back,” she wrote.
The post, shared on Tuesday 18 April, has been shared nearly 1,500 times in one day.
“This sounds so traumatic,” one person commented. “I’m so glad that he is ok. I am with you totally on making the packaging harder to open and a lot more obvious that they are extremely dangerous.”
Another wrote: “The wording on my packaging is quite bold but this is a good reminder for all parents. So sorry and hope he is doing ok.”
A spokesperson for Fairy told The Huffington Post UK: “We are very sorry to hear about this incident and sincerely hope the child is feeling much better now.
“Nothing is more important to us than the safety of the people who use our products and their families.
“Fairy Liquitabs are safe when used as intended: and we urge all parents to ensure all laundry detergents are adequately stored and kept away from children.
“We support the industry-education programme on the importance of safe use: information can be found on www.keepcapsfromkids.eu.”