Inflammation describes the reddening and swelling of a local area due to the effect of histamines, a first line of defense of the immune system. It's a common indication of possible infection, allergic reaction or an autoimmune disorder, and can manifest as a rash, hives, a red runny nose, or localized pain. It can range from merely annoying (such as an itch from an insect bite) to life threatening (anaphylactic shock).
Inflammation can be treated without knowing the underlying cause. Topical inflammation can be treated with ointments, such as petroleum jelly. Inflammation with mild pain can be treated with some painkillers, such as aspirin or ibuprofen (although acetaminophen should be avoided as it does not treat inflammation). For severe allergic reactions, adrenaline will reverse the histamine response and reduce the inflammation. For long term autoimmune disorders, such as lupus, steroids are required.