A new drug can ease the headaches, nausea and temporary infertility that afflict about 40 percent of the 1 million Americans with ulcerative colitis, doctors say.

Those side effects are the result of the sulfa drug sulfasalazine, the standard treatment for ulcerative colitis. The new drug, olsalazine, is equally effective against colitis but is not a sulfa drug.That means it doesn't have the side effects of sulfasalazine, said Dr. Stephen Targan of the University of California Los Angeles, although it does have milder side effects of its own. He is scientific adviser to the National Foundation for Ileitis and Colitis.

Ulcerative colitis, a severe inflammation of the colon, is characterized by diarrhea, rectal bleeding, weight loss and pain. It can occur at any age but often strikes people in their 20s.