Fluoride when given to swallow gets incorporated into forming teeth and makes them far stronger and resistant to decay for a lifetime. This is the most effective thing which can be done to prevent cavities - better than fluoride treatments or fluoride tooth paste. Check with your local health department. If you use well water, it may or may not contain naturally occurring fluoride and should really be tested to be sure. As winter approaches with it will come many colds and flu's.
Viruses have no specific treatment and generally run their course and go away with no harm done.
If your child gets a cold, cough, or congestion the most important thing is fluid. Make sure they are getting plenty to drink. For small infants a bulb syringe to clear the nose will help. Remember, the most important treatment is tender loving care and time. If you are sick, it will be that much harder to care for your child.