Taking herbal medicine as well as conventional drugs may help long-term hepatitis B sufferers, say researchers in California.

A study suggests Chinese herbal medicine on top of the standard treatment - interferon alfa - is better than interferon alone.

The analysis of 27 clinical trials - by a University of California, Berkeley, team - is published in the American Journal of Public Health.

"The results are encouraging enough that, if I had chronic hepatitis B and had previously failed interferon alfa treatment, I would talk to my doctor about combining interferon alfa with Chinese herbal medicine," says lead author Michael McCulloch.

Chronic infection

Hepatitis B is a type of liver disease caused by the hepatitis B virus.

Rarely liver failure develops which may need a transplant operation

If the infection lasts for more than six months, it is known as chronic hepatitis.

In this study, all the patients had the chronic form of the disease. Many were taking a variety of Chinese herbal medicines - including root, plant and toad extracts.

Some were also taking the standard treatment - interferon alpha, which can cause side effects like fatigue, depression and flu-like symptoms.

Overall, Chinese herbal medicine combined with interferon alpha was one-and-a-half to two times as effective as interferon alpha alone, says the Berkeley team.

But the researchers say they cannot make firm conclusions about the use of Chinese herbal medicines based upon the results from these clinical trials.

Risks and benefits

There is anecdotal evidence that herbs are useful in hepatitis either to improve general wellbeing or help with side effects, says Nigel Hughes, chief executive of UK charity the British Liver Trust.

But he says - like all treatments - herbal medicine has risks and benefits. He sees a need for more research, especially because small scale studies of Chinese herbal medicine have produced conflicting results.

"We need to know the mechanism of which herbs work and why," Mr Hughes told BBC News Online.

"We need large scale independent clinical trials of herbal treatments."

The World Health Organization estimates that two billion people around the world are infected with hepatitis B. About 350 million of these have the chronic form of the disease.