The most common cause of pus in the nose is infection located somewhere within the nasal cavity. Often this is caused by a primary illness that eventually escalates into a sinus infection. At other times, a sore or pimple can lead to pus inside the nose which comes from the sore itself. When caused by a sinus infection, other symptoms are often present. Most sinus infections will clear on their own without treatment, but some may need to be treated with antibiotics.
One common reason for having pus in the nose is a sinus infection. These usually occur when one has a cold or another respiratory illness. Bacteria or viruses can set up in the nasal cavities and lead to severe headaches, stuffy nose, runny nose, and sometimes pus drainage. Not all sinus infections will cause pus in the nose that one can see. Some people might also confuse pus with excessive mucus production in the nose.
Sinus infections are often treated with antibiotics, but these are not effective in all cases. Infections that are caused by viruses, rather than bacteria, will not response to antibiotic drugs. Patients who have a sinus infection should get as much rest as possible, and should blow their noses frequently to remove some of the bacteria or viruses. In most cases infections will heal naturally after a few days. Severe infections may eventually spread to the ears, leading to an ear infection.
Another possible cause of pus in the nose is a sore or pimple inside of the nasal cavity. This could occur due to injury, or a blocked pore or duct in the case of a pimple. Folliculitis, or infection of the hair follicles, can also occur. Staph bacteria is commonly found in the nose, and sometimes it can lead to infection in pores or sweat glands. This would lead to an eruption similar to a pimple commonly seen on the face. Pimples can also occur inside the nose.
If the pus is being caused by a sore inside the nose, it will usually resolve itself with time. Severe sores may have to treated with an antibiotic ointments, or oral antibiotics. Pain and bleeding may also occur. If sores last for more than a week or heal and then return, a doctor should be notified. More sores won't cause pus to ooze from the nose unless they have become severely infected. Pimples may "pop" and cause a small amount of pus to exit the nostril.