I used a naphazoline hydrochloride nasal spray after a nosebleed. i often get nosebleeds. is it dangerous?

This agent works by transiently reducing the size of blood vessels/capillaries. Recurrent use can injure the blood vessels and make them more likely to break. Limiting use to every other day or no more than 3 days in a we3ek can reduce the injury. The capillaries in the surface nasal membranes are fragile. Trauma/allergies are the main cause of bleeds. Your doc can verify/exclude any other issue

Recurrent nose bleeds may be due to bleeding disorder, or more commonly due to bleeding a small area with plexus of blood vessels. If the issue continues you may wish to see and ENT doctor to have the area cauterized.

In addition to the advice by the other doctors here, you can apply aquaphor or Vaseline (petroleum jelly) to the center inner areas of the nostrils (the septum). That is where the blood vessels are and keeping them moist may lessen the nosebleeds. A humidifier in the room where you sleep may also help. Sometimes the applicator of nasal sprays can be irritating and cause more bleeding.