I have a 3 month old baby which was diagnosed with whooping cough. he has been on anti biotics for 5 days but the cough is still the same. any advise on how to manage the cough ?

Patience: The cough of pertussis can last 3 months. If it is interfering with feeding/drinking/etc. close monitoring in a hospital setting may be required. The treating physicians can manage the cough as they see fit. There are few things that will help beyond simple mucolytic agents. None of the over the counter cough/cold meds have any value in this.

Prolonged illness: If there is any wheezing or prolonged cough > 3 weeks, recurrent fever, please consider a chest Radiograph. If there are any color changes, choking with color change or cessation of breathing, the baby should be seen in the Emergency Department.