Is Levolin Safe For Children Under 6 Years Old, Especially My Toddler?

Hi Doctors My son is about 2 years old and he have a tendency to cold and cough In every next day. Recently my doctor prescribed him nebulizing with Levolin 0.31mg. I found after some research that Levolin. 0.31 is NOT for less than 6 year old infants. So my question is, that Levolin is safe or not for less than 6 years old infants??