How long does it rob to know if your kids are sick?

my twins have flem contained by their throat.How long does it rob to know if your kids are sick?
Depends on the color. If it is clear, it might be secretions that are merely flushing out allergens or if it is green or sickly it is likelier to be an infection. This would be accompanied by frenzy (perhaps). If they are not running a temp. they are likely to be okay, but if it persist call their pediatrician.
Check for hallucination, that's when they are sick.