Bacteria may cause pimples and boils (furuncles) to form just inside the opening of each nostril (the nasal vestibule).
Nasal vestibulitis
Minor infections at the opening of the nose, called nasal vestibulitis, may result in pimples at the base of nasal hairs (folliculitis) and sometimes crusts around the nostrils. The cause is usually the bacteria Staphylococcus. The infection may result from nose picking or excessive nose blowing and causes annoying crusts and bleeding when the crusts slough off.
Nasal furuncles
More serious infections result in boils (furuncles) in the nasal vestibule. Nasal furuncles may develop into a spreading infection under the skin (cellulitis) at the tip of the nose. A doctor becomes concerned about infections in this part of the face because veins lead from there to the brain. A life-threatening condition called cavernous sinus thrombosis can develop if the bacteria spread to the brain through these veins.