How soon can i give my 4 year old ibuprofen after giving delsym (dextromethorphan) cold and cough?

Follow guidelines: This has an antihistamine and decongestant in the formula. Not knowing the weight of your child i would wait at least an hour. If the child is asleep let them sleep if not then give the ibuprofin according to the package directions for children and see/call your pediatrician asap. Rest and fluids with meds as needed; more is not better stay with in the guidelines for safety.