When a child sinuses are blocked with discharge, bacteria may start to grow. This leads to a sinus infection or sinusitis. The most common bacteria that cause acute sinusitis include: streptococcus pneumonia, haemophilus influenza, moraxellla catarrhalis

Symptoms

Common signs:
• Thick yellow or greenish mucus from the nose (runny nose) or down the back of the throat ( postnasal drainage)
• Blocked or stuffy nose (congested) causing difficulty breathing from the nose
• Pain, tenderness, swelling and pressure around the eyes, cheeks, nose or forehead

Other signs and symptoms:
• Ear pressure
• Loss of smell
• Cough
• Fever

Otomar benefits 

Nasal saline irrigation may reduce the need for pain medication and improve overall patient comfort, particularly with patients with frequent sinus infections.
Normal saline irrigation in children with allergies improves their symptoms and the development of acute infections.
Studies have shown that nasal irrigation with isotonic and hypertonic solutions provide benefits for symptom relief.
Research suggests that intranasal saline spray may temporarily improve nasal passage patency by moisturizing and loosening secretion. This approach may be useful in combination with intranasal steroids.


Reference:
Y.-H. Wang et al. Efficacy of nasal irrigation in the treatment of acute sinusitis in children. International journal of pediatric otorhinolaryngology 73(2009) 1696-1701