Abbott Laboratories Inc. said Friday the Food and Drug Administration approved its drug Humira as a treatment for ulcerative colitis in adults.

The FDA approved Humira as a treatment for moderate to severe ulcerative colitis when other medicines have not worked. Abbott said around 700,000 people in the U.S. have the disease, and symptoms include abdominal cramping, rectal bleeding, diarrhea, and urgent and frequent bowel movements.

Humira is already Abbott’s biggest-selling drug. U.S. sales totaled $1.83 billion in the first six months of 2012. Worldwide revenue from the drug totaled $4.26 billion, a large chunk of Abbott’s total revenue of $19.26 billion over that period.

Humira is also approved as a treatment for chronic plaque psoriasis and as a treatment for symptoms of rheumatoid arthritis, psoriatic arthritis, juvenile idiopathic arthritis, and Crohn’s disease, a type of inflammatory bowel disease.

Shares of Abbott Labs lost 76 cents to close Friday at $68.56.