Clinical Experience with Da Qinglong Tang (Major Bluegreen Dragon Decoction)
Da Qinglong Tang is a classical formula from Zhang Zhongjing's Shanghan Lun. The original formula: Mahuang six liang (nodes removed), Guizhi two liang (peel removed), Zhi Gancao (honey-fried licorice) two liang, Xingren forty pieces (tips and peel removed), Shengjiang three liang (sliced), Dazao ten pieces (broken), Shigao (gypsum) as large as a chicken egg (broken). Boil the seven ingredients in two sheng of water; first boil Mahuang, reducing by two sheng, skim the foam; add the other herbs and boil to three sheng, strain, take one sheng warm, to induce a slight sweat.
The Shanghan Lun gives its indications: "In taiyang wind-strike, with floating, tight pulse, fever and aversion to cold, body pain, absence of sweating and irritability, Da Qinglong Tang governs. If the pulse is weak, with sweating and aversion to wind, it must not be taken; taking it will cause reversal, twitching of sinews and flesh—this is adverse. Also: cold damage, floating, moderate pulse, body not painful but heavy, now and then lightened, with no shaoyin pattern."
Like Mahuang Tang, Da Qinglong Tang is a potent sudorific. Used wrongly, it can cause loss of yang through profuse sweating; the patient not only fails to recover but rapidly becomes critical, so many physicians fear it and dare not use it. Its main indication is internal heat with exterior cold: aversion to cold and fever are exterior signs after external contraction of wind-cold, requiring acrid-warm herbs to dispel it. Irritability signals internal heat, which may come from pre-existing constrained heat (no wind-cold attacks without internal fire)—some patients contract wind-cold precisely because internal constrained heat disrupts the exterior-interior and nutritive-defense flow. Or the external wind-cold may transform into heat, so that cold locks the exterior while heat binds the interior.
Severe internal heat injures the qi aspect, producing irritability and thirst, constipation, abdominal pain, nausea, vomiting and belching. Because the patient cannot sweat, Baihu Tang is inappropriate. If one uses only Mahuang Tang—all acrid-warm, with nothing to clear internal heat—the patient will sweat, but acrid-warmty feeds the heat: the interior remains unresolved even as the exterior is released, and the illness does not ease. Hence the addition, on top of Mahuang Tang, of large raw gypsum to clear qi-aspect heat—"as large as a chicken egg."
My own son recently caught a cold; being small, he refused herbal decoction. I started with Western medicine, but after three days he worsened: ibuprofen and other antipyretics brought not a sweat, his temperature kept climbing to 40°C and would not break. He was restless, awake all night, constipated with bad breath, severely congested and runny-nosed and thirsty. He refused acupuncture, so with no other choice I forced the decoction on him. I prescribed Da Qinglong Tang plus Tianhuafen (Trichosanthes root) and Xinyihua (Magnolia flower).
Mahuang 12 g; Guizhi 6 g; Zhi Gancao 4 g; Xingren 6 g; Sheng Shigao (raw gypsum) 12 g; Tianhuafen 12 g; Xinyihua 3 g.
Decoct to two cups; he drank one cup first. Within minutes his whole body felt roasted by fire, as hot as a live coal; my son, low on tolerance, wailed loudly. Half an hour later he was drenched in sweat, which I wiped dry with a towel. Afterward he had chapped lips, bleeding gums and sore throat—"upper fire" signs—but an hour and a half after dosing the illness was gone. The persistent fever broke; I observed him overnight, he did not fever again, and I did not give more herbs. That was a bit careless, so the next day when feverishness began again I gave him half of the remaining decoction; in about half an hour a slight sweat appeared, the fever was intercepted, and his spirit and strength returned. This time there were no "upper fire" signs; he only said his body felt warm, no longer chilled, and there was no longer that hot-coal sensation of the first dose.
The doses I used are the currently recommended clinical amounts; I did not convert one liang to 15 g as Li Ke advocated. Even at these slightly larger doses the side effects were this strong; had I used Li Ke's doses, I believe an adult could not tolerate them either.
Da Qinglong Tang acts remarkably fast; with accurate pattern differentiation, a single dose can cure a heavy cold—an effect Western medicine cannot match. But its side effects are equally strong; in practice the dose must be carefully controlled, or treatment itself causes the patient suffering.