Korn has been forced to cancel its European tour due to a blood-related illness suffered by frontman Jonathan Davis, who was hospitalized in London over the weekend. The group played a shortened set on Saturday at the U.K.'s Download Festival with the help of guest vocalists from Slipknot, Devildriver, 10 Years, Skindred and Avenged Sevenfold.

Davis is suffering from the blood disorder immune thrombocytopenic purpura and has been ordered by doctors not to perform for several weeks, necessitating scrapping dates through July 2 in Leipzig, Germany. The band is hoping to reschedule the shows later this year.

"I started getting these weird bruises all over my body about two weeks ago," Davis wrote in a post on Korn's Web site. "I was getting very weak after the shows so I saw a doctor in London Friday. He took some blood tests and when the results came in, they rushed me to the hospital. It turned out that I have ITP ... a blood infection where, because of an allergic reaction I had to some medication, my blood platelets were really low. If I continued to headbang onstage, I could have had a brain hemorrhage and dropped dead on the spot."

Davis' illness is not expected to affect the band's Family Values tour, which is due to begin July 27 in Virginia Beach, Va. Deftones, Stone Sour, Flyleaf and Dir En Gray will also be on the bill.