Chinese herbal medicines are offered in a variety of formats. Traditionally teas comprised of carefully measured amounts of individual herbs were used more often and are common today. In part to ease storage and patient administration many formulas are now available in granules and pill form (tablets (pian), balls (wan), capsules, etc.). One might assume that using the formulas in a tea form would better preserve many of the oils and other substances in the herbs that would lead to better results. Also the teas are assumed by some to avoid the granules/pills not being properly assimilated. Researchers from the Center for Evidence Based Chinese Medicine at Beijing University recently conducted a systematic review of clinical trials involving both teas and prepared formulas in granule form to see if there were obvious clinical differences.
Looking over 56 clinical trials from China they found that there were little clinical differences that appeared between prepared formulas vs. teas. With the relatively small sample size, however, it is difficult to draw conclusive arguments.
From my perspective, particularly in the west, I have seen the patient compliance is much, much higher with granules/pills vs. boiling raw herbal teas. For this reason alone, even with a possible minor difference in effectiveness there should be no hesitation in using prepared formulas. Yet from these studies the differences seem to not be an issue. More studies would have to be done, however, comparing herbal preparation options head to head with the same cases.