(HealthDay News) -- Sinusitis occurs when the air-filled cavities inside the skull become inflamed.

The University of Maryland Medical Center says these factors increase your child's risk of developing sinusitis:

• Having hay fever or allergic rhinitis (a stuffy or runny nose often accompanied by itchy eyes and post-nasal drip).
• Being in daycare.
• Having a condition that affects the cilia (small hairs in the sinuses).
• Undergoing altitude changes, such as those that occur during air travel or scuba diving.
• Having enlarged adenoids, or rarely, an infected tooth.
• Having a immune system that's compromised by chemotherapy, HIV infection or other conditions.
• Having cystic fibrosis, an inherited disease that results in thick, sticky mucus in the lungs and digestive tract.