Is light bleeding from the nose for a short time dangerous ?what could be the causes of this ? thanks :)

Trace nose bleeds: I see this a lot with steroid nosesprays. A thorough examination is important. Trace of blood could be from low humidity, nosesprays, cocaine, trauma, virus, foreign body. Could have prominent blood vessel that needs cautery. But significant or recurrent ones need to be seen by professional and labs ordered; can be serious (e.g. leukemia).