I gave my daughter donatussin for a cough 2 hours ago. she is still coughing. can i now give her benadryl (diphenhydramine)? she is 3 yrs old and 39 lbs.

Don't use donatussin: Cough suppressants (like donatussin) have been shown not to work in kids and actually can cause side effects. From now on, i would not recommend any cough suppressants for your child. There seem to be various formulations of donatussin, so make sure they don't already contain Diphenhydramine (benadryl). I hope she feels better.