​Febuxostat belongs to a class of medicines called xanthine oxidase inhibitor which lower uric acid (also called urate) levels in the blood.  The other xanthine oxidase inhibitor is allopurinol. Usually you are prescribed Febuxostat if allopurinol is unsuitable for you.

When the uric acid builds up in the blood and becomes too high, urate crystals may form in and around the joints (such as big toe joints, ankles, elbows). These crystals irritate the tissues and cause sudden, severe pain, redness, warmth and swelling in a joint, commonly known as a gout flare or attack. Left untreated, larger deposits called tophi may form in and around joints. These tophi may cause joint and bone damage.

Febuxostat is used for reducing uric acid levels, stopping crystal formation and dissolving crystal for excretion. Over time, it reduces gout flare and associated symptoms. Keeping uric acid levels sufficiently low for a long enough period can also shrink tophi.