hello and welcome to health care magic, The number one cause of nose bleed in this age is nose picking. Most parents will claim that their kids do not do nose picking which is simply not possible! Before going for a radical procedure like cauterisation which is essentially done in acute severe bleed and mostly in adults and is not a permanent solution; you must first try the non invasive methods. In any case if it is a nose bleed get an ENT consult and not a pediatric one as to each his own but though cauterization in good hands is relatively safe, I would not recommend the same foe a 4 year old kid. Hope this helps and if you want to know about better treatment which are non invasive for nose bleeds then you can get back to me regards Dr Sriram Nathan