It has to be noted that common cold doesn't go instantly at all. It has its time which is around a week and it is made sure to take that long. But there are some tips parents can do to prevent it and to bring it to control. Some ideas I tried and did work would be as follows:
1) the holy basil or tulsi, is actually a herb. Always make sure to boil the drinking water with a few leaves of basil leaves in it and only use this water for drinking purpose. This solves the problem to a maximum level. Preschooler's parents please follow this point.
2) if your baby has running nose or stuffy nose, use paediatric nasal drops. It helps even if it is running nose.
3) Try doing steaming. If your babies don't opt it, a technique i follow would be, i put some leaves or something in the steamer or make a mark on the steamer and try showing it to her while she un knowingly steams. Also if possible, place some holy basil leaves "OVER the steamer" where the steam come. It helps to a huge extend.
4) Rub, vicks or other such vaporizers very lightly over their chest, back, sides, throat, behind the ears. and try making them inhale its fumes.
5) make sure to clean the floor with "dettol" or other such sanitizers and not floor cleaners.
6) while going through the phase, drop a few of detol or which ever sanitizers used around the area where the baby sleeps.
7) also, if following any medications as per your baby's pediatrician, please make sure to complette each coarse.
I follow these steps and it does help.