Does it matter if a child's nasal snot is green or clear, when he has cold symptoms?

Nasal congestion. The common wisdom for decades has been that discolored nasal secretiions indicate a bacterial infection requiring antibiotic treatment. It turns out that myeloperoxidase in white blood cells often cause such discoloration in nasal secretions on days 3-6 of many uncomplicated viral infections that will clear spontaneously without antibiotic treatment by day 10-12.