More than one quarter of HIV-positive Americans also have hepatitis C (HCV). A new study shows that if you are coinfected, and if HCV therapy gets your hepatitis viral load to undetectable after four weeks, you may well succeed in clearing HCV. But what if you’re not among the undetectables?

Standard hep C therapy for coinfected people is pegylated interferon (Pegasys, Peg-Intron) and ribavirin (Rebetol, Copegus) for 48 weeks. This routine often fails, especially in those with the common, hard-to-treat HCV genotype 1 strain. The therapy also has some miserable side effects including fatigue, muscle aches, anemia and depression.

If HCV isn’t undetectable at four weeks, says Mark Sulkowski, MD, of Baltimore’s Johns Hopkins Medical School, tests at eight and then 12 weeks may show improvement. “If there continues to be no significant reduction and viral load is about 500,000,” he says, “I’ll stop treatment.”

Some researchers think the therapy benefits liver health even when it doesn’t clear HCV. But Raymond Chung, MD, of Harvard Medical School, says this may not work for HIV/HCV coinfection—and a study released at the February ’08 Conference on Retroviruses and Opportunistic Infections backs him up. For people battered by those infamous side effects (like “the flu from hell,” say some who’ve been there), quitting the drugs may offset the disappointment of failure.

Both Sulkowski and Chung agree that if you’re not among the success stories, there are steps you can take to boost the health of your liver: Avoid alcohol, keep your weight and body-mass index within healthy limits, and control your HIV. They add that new HCV treatments, including protease inhibitors, are being studied, and that diabetes drugs are also under examination for hep C therapy.

Diabetes meds may help promote HCV treatment success by improving one source of liver damage, fatty liver. And if you’re recently diagnosed with HCV, note that starting treatment early seems to work best.