What could cause random nose bleeds?

A few things. Most nosebleeds do not have an easily identifiable cause. Trauma to inside of the nose from nose picking very common. Other causes are exposure to warm, dry air for prolonged periods of time, nasal/sinus infections, allergic rhinitis, nasal foreign body (object stuck in nose), vigorous nose blowing, nasal surgery, deviated/perforated nasal septum, and cocaine use. See ENT doc for exam/treatment.

Related Questions

Someone I know is having a nose bleed for about 20 minutes and he gets these nose bleeds randomly for about 4 days now & can he do anything for this?

He needs testing. Unless there is obvious trauma to the nose, he needs to have blood work, starting with his primary care doctor, to include a cbc, PTT and inr .. Read more...
Blood work. It could be the result of a cold or infection or something more. His doc can do some blood work to see if your friend has difficulty clotting and help if needed. That help could be medicine or diet modification. Read more...