Alex has a chest infection and fever. i have accidently given him the wrong paracetamol. 4ml of 250mg/5ml rather than 3 ml of 120mg/5ml. should i be concerned. ?

Need more info: How much does he weigh? The standard dosing is 10-15 mg/kg. If his dose was supposed to be ~70-100 mg, then he received double that. Don't give him any more for at least 12 hours, but it is unlikely that a single dose of 200 mg will cause significant harm.

Yes, some concern:: Paracetamol is toxic to the liver. The dose you gave is 200 mg instead of 72 mg so almost 3 times the advised dose. A single dose may not be too damaging but I strongly advise giving N-acetylcysteine (NAC) 140 mg/kg ASAP; you can find this at health food stores (if not the ER will have it). See http://tinyurl.com/jkm5m6n Know that lowering fever prolongs illness! See http://tinyurl.com/y7a84ph8

Can call doctor: It also depends on a baby's age, medical issues, weight, etc. Most likely, this scenario is okay, and one can just skip paracetamol for the next 18-24 hours. That is because the usual dose is 15mg per kg of baby weight, meaning 72mg is enough for a 5 kg baby. The toxic dose is 10 (ten) times that, meaning the toxic dose is 720mg. That means 200mg is unlikely to cause any noticeable problem.