If i have given my 3 year old hylands cold and cough for kids can i also giver her benadryl (diphenhydramine) if the hylands is not working?

Caution: Benadryl (diphenhydramine) is an antihistamine that can help with runny nose and sneezing due to allergies. It does have a sedation effect in many. American Academy of Pediatrics discourages the use of cough medications in any child under 6 years old. The benadryl (diphenhydramine) may cause her to be too sedated and may have some breathing troubles in the night. Try cool mist humidifer - warm water/mixed with honey and patience.