What is the reason for a 4-year-old boy's nosebleed?

Patient's question:

No

Doctor's answer:

There are many reasons for nosebleeds, but about half of the people cannot find the cause. The capillaries in the nasal mucosa are densely distributed, very sensitive and fragile, and are easily broken, leading to bleeding. Reasons for nosebleeds are many, including nose trauma, mucus