My 8 year old son swallowed an advil (ibuprofen) gel 400 mg. by mistake. will that effect him. what should i do.

Advil (ibuprofen): Advil (ibuprofen) is dosed according to weight and it is the Ibuprofen component that we are concerned about. A child can take up to 10 mg per kg in single dose.

Unlikely if 1 time: If he is an average wt kid (25kg) that exceeds the recommended dose (5-10mg/kg) but should not be a problem if it is a one time exposure.It would be used at that level in treating some uncommon inflammatory diseases in kids.