Modified Taohua Tang (Peach-Blossom Decoction) for Radiation Enteritis
Some cancer patients develop radiation enteritis after radiotherapy as a sequela—long-term diarrhea with blood in the stool, which over time also causes anemia. Radiation enteritis is hard to treat; neither Chinese nor Western medicine has a particularly good solution. On the basis of Taohua Tang (Peach-Blossom Decoction) from the Shanghan Lun, I added some herbs to form a modified Taohua Tang that has helped some radiation enteritis patients.
The original Taohua Tang formula: Halloysitum rubrum (Chishi Zhi) 1 jin (half used raw, half sifted into powder), dried ginger (Ganjiang) 1 liang, rice (Jingmi) 1 jin. Here jin and liang are Han-dynasty units: one Han jin is about 250 g today, one Han liang about 15 g, and one Han jin equals 16 liang. But we generally do not use that much: Halloysitum 30–60 g (half decocted, half ground and infused), dried ginger 1–6 g, rice 30–60 g. For the rice I use Northeast long-grain rice.
The main component of Halloysitum rubrum is aluminum silicate tetrahydrate; like the montmorillonite in montmorillonite powder, it is an aluminum-silicate compound. Aluminum silicate coats the intestinal mucosa and effectively blocks viruses and bacteria from attacking it, producing an antidiarrheal effect. That is how Halloysitum stops diarrhea.
But Taohua Tang works better than montmorillonite powder, because it contains not only Halloysitum but also dried ginger and rice water. Dried ginger itself also stops diarrhea; patients who tell me they have had loose stools year-round are advised to brew dried ginger tea, and this single herb alone can cure such chronic diarrhea. Ginger is a foodstuff with very few side effects. TCM holds that dried ginger warms yang, so adding it improves the yang-warming, diarrhea-stopping effect. The rice water protects the gastrointestinal mucosa and also restores the patient's strength. The three together stop diarrhea even better.
In the Shanghan Lun, Taohua Tang treats Shaoyin disease: "In Shaoyin disease, when there is diarrhea with pus and blood in the stool, Taohua Tang governs it." Shaoyin disease is characterized by a fine, faint pulse (my note: the vast majority of radiation enteritis patients can be identified as having a fine, faint pulse without taking it, because they mostly have long-term bloody diarrhea, are very weak, and often need transfusions to stay alive; such patients all have a fine, faint pulse). Another feature is listlessness (called "but desire to sleep" in the Shanghan Lun), which radiation enteritis patients also exhibit. So radiation enteritis fits Taohua Tang's indications well.
But Taohua Tang alone is not enough to address radiation enteritis patients' anemia. I combine it with Danggui Buxue Tang (Angelica Blood-Supplementing Decoction) and Shengmai San (Pulse-Generating Powder): add ginseng (Renshen) 3–10 g, Ophiopogon (Maidong) 6–10 g, Schisandra (Wuweizi) 6–10 g, raw Astragalus (Sheng Huangqi) 30–60 g, Angelica (Danggui) 6–12 g, which both stops diarrhea and nourishes blood. I also tell the patient to take some oral iron supplements or medicine, because anemic patients are iron-deficient. This addresses both diarrhea and anemia.
Aluminum silicate has essentially no side effects, but once diarrhea has stopped, continuing it causes constipation. So when using this formula for radiation enteritis, I warn the patient: once diarrhea stops, Halloysitum should be discontinued, and the later stage best switched to Shenling Baizhu San and Guipi Wan for aftercare.