Thanks for posting your query here.
I am really glad to hear that your son is doing well today.
The dose he took is definitely above the recommended dose. Symptoms usually are very fast heart beating, tremors, vomiting
or sweating. Symptoms don't tend to last longer than 24 hours usually.
From your description, it seems he did not have any alarming symptoms described above. Please be reassured.
However, I would suggest extra vigilance should any symptoms develop and seek medical help
immediately if symptoms appear.
I am really surprised that a 6 year old would do such a thing. (This sort of overdosage are common especially around age of 2-3 years, when kids get hold of a bottle and drink it considering water or juice).
Dr Tejas Shah
Critical Care Specialist