As you know, common cold is a set of symptoms which is most common among children, and it is caused by a set of viruses, to name few, rhinovirus, parainfluenza virus, coronavirus, respiratory syncytial virus, adenovirus, influenza virus etc. Since it is caused by hundreds of types of viruses, it is difficult to develop a common vaccine for common cold. As you get immune from one virus, another one may attack your children. An interesting statistics shows that, children less than seven stay affected by common cold, almost half of the days in the Sept-April period. The symptoms may last for average 14 days. So, it may give impression that your child is always ill, but, you don't need to worry as long as it does not turn into some serious bacterial infection.
First 3-4 days may have fever (temperature greater than 100.4 degree F or 38 degree C) as well. During this period, they may exhibit symptoms like nasal congestion, nasal discharge, sore throat, difficulty to sleep and decreased appetite.
Now, let's look at how to treat this. As a general rule, a common cold should disappear within 10 to 14 days of its appearance, even without any medication. Still, there are medications available for infants and children, e.g. decongestants, antihistamines, cough medicines, and expectorants. However, their benefits are not yet clinically proven. The best thing that you can do is to stay away from the things which could accelerate the symptoms. Like, cold climate could accelerate the symptoms, and fewer intakes of fluids could also worsen the symptoms; however, it is not advised to drink more than what's required.
Use of antibiotics is not at all advised, unless there is a bacterial infection (ear infection, pneumonia, or sinusitis), mainly because, inappropriate use of antibiotics may develop resistance to it or even allergic symptoms.
Since common cold is contagious, children may largely get affected when they are in day-care or school. So, teaching them the hygienic ways to prevent this from spreading will definitely help. The affected person may carry the virus on his hands, or the air surrounding him through un-protected sneezing or coughing. The virus can stay active on your hands for about 2 hours, if a human or anything else comes in contact with their hands, the virus could possibly transmit to that person or object. Some cold viruses can even stay on surfaces for weeks. So, cleaning the surfaces that may come in contact with the affected person is also a good way to prevent this from spreading.
To conclude, it is advised to keep the affected person's hands clean by washing several times a day with soap. Fever relievers for the first few days would be enough, mostly, and, proper rest for few days is also recommended. But, if it does not show any sign of relief even after 10-14 days or the fever couldn't be controlled, then you must get help from your physician as soon as possible. If properly kept in check, common cold would last only for few days, until it again appears, for sure in case of infants and children.