how can I reduce the cold and fever infections for 3 year old boy.what are the preventive remedies to control severe cold?

A. Cold is most of the time because of viral illness and if the child is having recurrent running nose and nasal congestion it may be a part of allergic condition and needs a proper evaluation. steam inhalation will be very effective. decongestant medicine like ascoril flu / wikoryl / sinarest can be given. viral cillness could also have associated symptoms like cough and fever which needs treatment accordingly.