"I'm still confused after all these decisions," said the 49-year-old Dr. Medenica, who was one of the first doctors in the world to use interferon in cancer therapy.

If you use both interferon and ribavirin, tooth and gum problems may sometimes occur.

In a study of patients at Abundant Life clinics in Washington and New York, Dr. Muhammad and another doctor, Barbara Justice, said that 82 percent of AIDS patients using low-dose alpha interferon experienced increased appetite and other improvement.

Dr. Tsai, who was trained in Western medicine, became frustrated with poor results when using interferon to treat patients with hepatitis B, Mr. Hwang said.

If you use both interferon and ribavirin, you may quickly develop a certain serious blood problem (anemia).

Combination therapy using interferon and ribavirin is now approved by the U.S. Food and Drug Administration for use in children ages 3 to 17 years.

"We know how to use interferon," he added.

A flu vaccine that uses interferon as adjuvant is currently under clinical trials in the US.

An alternative to using interferon itself as an anti-viral drug is to use chemicals that induce cells to make their own interferon.

Before using interferon, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies.