So first, treating addiction requires professional intervention and a complete willingness by the person experiencing addiction to want help. That is, you wanting to help them is noble, but will ultimately not lead to much unless they seek the help out themselves. Hard but true.
Ge gen has shown some limited value in research with regards to the effects of alcohol and addiction generally. The best benefits are usually in proper combination with other herbs in a formula tailored over time to the individual (see “how to choose a formula” for general info). This, of course, coupled with western intervention (medical detox if necessary) and then counseling, etc.
The following lengthy clinical publication entitled “Alcohol use disorders and current pharmacological therapies: the role of GABAA receptors” discusses some of the research around the usages of herbs within the Chinese system and why they may have potential for benefit. Again, single herbs are often not very beneficial compared to properly tailored formulas - so your friends, should they want help, should seek out regular visits with a fully trained practitioner of Chinese Medicine who can monitor their progress and tailor formulas directly for them. Many, many practitioners are offering online treatments which is fairly straightforward when you are using only herbal medicine, but I would still find someone in their area so they can see them in person later, even if the treatments start online.
With regards to kudzu and its relation to arrowroot - kudzu is sometimes called “Japanese arrowroot” or “East Asian arrowroot” but for most purchasers arrowroot and kudzu are different things all together. Arrowroot is often made from a range of plant tubers, so if you are going for kudzu that is what you would want.
It is extremely important that they start with general bloodwork (liver function particularly) and then monitor this over time to avoid even worse problems from the herbal treatment itself. Many of these approaches can be problematic when mixed with alcohol and/or taken in too high amounts - so honesty with a practitioner is critical - this is one of many reasons they need to be 100% on board to get help.