Sometimes blood vessels inside the nose become irritated and don't heal. This happens frequently in teens who have ongoing allergies or frequent colds. Don't blow forcefully or pick your nose. Your doctor may recommend a humidifier, which moistens indoor air. You can also prevent your nasal passages from becoming too dry in winter months by using lubricants such as petroleum jelly before going to bed at night.
Some doctors prescribe saline drops for the same purpose.
Hand washing, when done correctly, is the single most effective way to prevent the spread of communicable diseases. Good hand washing technique is easy to learn and can significantly reduce the spread of infectious diseases in both children and adults. Diseases spread through fecal-oral transmission. Infections which may be transmitted through this route include salmonella, shigella, hepatitis A, giardia, enterovirus, amebiasis, campylobacter, etc. Diseases spread through indirect transmission.