Didn't realise cough medicine I've been giving DS, is not recommended for under 12s

[creole]

DS had a bad cough since friday, so gave him some cough medicine which I thought were his. Benylin chesty cough - it was three-quarters full. We finished the bottle 2 days ago. However, just realised the cough medicine was one of mine.

Should I be worried?

I took him to the docs today as the cough didn't get better and he was prescribed antibiotics. The docs confirmed that he had a chest infection, so he's on a 7 day course.

BTW, DS is 8 years old.

I don't think i would worry with an 8 yr old but maybe phone NHS direct and see what they say?

Thanks for replying, I was stupid for not looking at the instructions, I just thought it was one of his. I will most definately check next time...It could have been fatal.

I wonder though, if anyone else has made this mistake.