Unfortunately, there’s no quick and easy way to dry up a toddler’s runny nose. Although anti-histamines may stop the drainage, they can also clog up the nose and keep the mucus from draining away germs. A runny nose can become a sign of a more serious infection such as sinusitis, an upper respiratory infection. But nasal discharge can continue for several days and even weeks without necessarily indicating sinusitis. It’s best to let a doctor diagnose a respiratory infection rather than self-administer antibiotics on a hunch. Overusing antibiotics can create resistant strains of germs, which then require even stronger and more expensive antibiotics. So in the case of a long-running nose, it’s best to let each nose run its course.