How does Allopurinol treat kidney stones?

The buildup of minerals and salts inside your kidneys may form a small, hard deposit known as a kidney stone. Several types of kidney stones may form, depending on the type of mineral or salt responsible for the buildup. If uric acid builds up in your bloodstream, uric acid stones may form in your kidneys. Allopurinol lowers the level of uric acid in your bloodstream by preventing your body from producing uric acid. While allopurinol cannot treat kidney stones once they occur, allopurinol can lower levels of uric acid and help prevent a reoccurrence of kidney stones.