Skip to main content

Study designs of randomized controlled trials not based on Chinese medicine theory are improper


Current biomedical research methods to evaluate the efficacy of Chinese medicine interventions are often conceptually incompatible with the theory and clinical practice of Chinese medicine. In this commentary, we (1) highlight the theory and principles underlying Chinese medicine clinical practice; (2) use ginseng as an example to describe clinical indications in Chinese medicine; (3) propose a framework guided by Chinese medicine theory for the evaluation of study designs in Chinese medicine research; and (4) evaluate 19 randomized, double-blind, placebo-controlled trials of ginseng. Our analysis indicates that all 19 trials with both positive and negative results confirm the specific effects of ginseng indicated by Chinese medicine theory. Study designs guided by Chinese medicine theory are necessary to validate and improve future randomized controlled clinical trials in Chinese medicine.


Chinese medicine remains popular in China where traditional herbal preparations are estimated to account for 30–50% of the total medicinal consumption [1]. Chinese medicine has also been gaining popularity in the West [13]. However, Chinese medicine lacks funding and leading scientists to conduct scientific research (e.g. randomized controlled trials) [4].

The study of ginseng provides an example of the research challenges in Chinese medicine. Highly valued in the Chinese medicine classics and widely used in China for more than two thousand years, ginseng has yet to prove its safety and efficacy through clinical trials [5, 6], which, many investigators believe, may be attributed to a paradigm conflict and the poor quality of some clinical trials [7, 8].

We found that this paradigm conflict may be resolved by using study designs guided by Chinese medicine theory.

Chinese medicine theory

Chinese medicine is a syndrome-oriented holistic medical system that is conceptually distinct from its Western counterpart. According to Chinese medicine theory, a syndrome is a group of associated signs and symptoms described in terms of Yin and Yang, Qi, and Xue (blood) [9]. All illnesses fall into eight principal categories used to guide the prevention and treatment of illnesses [10]. These categories are Yin and Yang, Biao (exterior) and Li (interior), Han (coldness) and Re (heat), and Xu (deficiency) and Shi (excess). Western medicine, however, views a disease or syndrome as pathological changes of specific biological processes [1]. As a result, the syndromes in Chinese medicine do not always correspond with Western classifications of diseases and syndromes. For instance, hypertension may be related to syndromes of Gan (liver) Yang ascending, Yin deficiency of liver and kidney, flaming liver fire, stagnation of phlegm, Xue stasis and/or dual Yin/Yang deficiency [11]. Conversely, Qi-deficiency syndrome is related to chronic obstructive pulmonary disease [12], lung cancer [13], coronary heart disease [14] and persistent allergic rhinitis [15].

Herbal medications

In Chinese medicine, medicinal herbs are categorized according to the concepts of Yin, Yang, Qi, Xue, Jing (essence) and Jin (body fluid) [16]. In general, 'tonics' are used to treat deficiency and 'clear-ups' are used to treat excess [9].

Considered the premium Qi-tonifying herb to treat various illnesses [16], ginseng is thought to have the major indications as follows:

  1. (1)

    Impalpable pulse caused by severe Qi-deficiency;

  2. (2)

    Shortness of breath, feeble voice, spontaneous sweating and a weak pulse caused by Fei (lung) Qi-deficiency;

  3. (3)

    Fatigue, anorexia and loose bowels caused by Pi (spleen) Qi-deficiency;

  4. (4)

    Fever and strong thirst caused by Qi-deficiency;

  5. (5)

    Palpitation, insomnia and forgetfulness caused by dual deficiency of Qi and Xue.

Study design compatible with Chinese medicine theory

Research topics

Instead of evaluating the efficacy of ginseng in all patients suffering from a single disease, researchers should focus on those patients with Qi-deficiency syndrome. Qi-deficiency causes decreased visceral functions and lowered immune resistance, leading to various diseases. The manifestations of Qi-deficiency include lassitude, shortness of breath, feeble voice, dizziness, spontaneous perspiration, susceptibility to cold, pale tongue and weak pulse [10].


Chinese medicine practitioners prescribe herbal medications to rectify disharmony in a patient's system [16]. Healthy individuals should not participate in treatment groups in Chinese medicine studies. This explains the negative results from the ginseng studies in which healthy individuals participated [1721].

Ginseng is a Qi-tonifying herb to treat five major syndromes [16] caused by Qi-deficiency. Therefore, we argue that only studies in which participants are diagnosed with Qi-deficiency are valid to evaluate ginseng's efficacy [2225].

Herbal species

While at least eight species of ginseng are commercially available [26], only two major species, namely Panax ginseng (Chinese or Korean ginseng) and Panax quinquefolius (American ginseng), are used as medicinal herbs worldwide. According to Chinese medicine theory, the properties and functions of these two species are quite different [16]. While P. ginseng enhances Yang, P. quinquefolius nourishes Yin. A search for randomized controlled trials of ginseng in PubMed (7 September 2008) found that about one-third of the studies did not mention the ginseng species used and that very few studies addressed the species issue.

Herbal quality

Herbal quality may affect research results. Different batches of P. ginseng [27, 28] or P. quinquefolius [29] produced opposing study results respectively on acute postprandial glycemia. The primary active ingredients in ginseng are ginsenosides. G115, a ginsenoside-based standardized extract of P. ginseng, may help assess the efficacy and safety of ginseng. In fact, G115 was used in most P. ginseng (single herb) trials reviewed in this paper.

Herbal formulae

In Chinese medicine, herbs are often formulated to achieve increased therapeutic effects and reduced toxicity or side effects [16]. Results from clinical trials on herbal formulae confirm this practice. A Japanese trial found that a 7-herb formula was effective in preventing liver cancer in cirrhosis patients [30]. Two British trials showed that a 10-herb formula was effective in treating a severe atopic eczema [31, 32]. No single herbal ingredient explains the efficacy in these studies [33]. Furthermore, ginseng herbal formulae were shown to be effective in treating chronic pulmonary disease [22, 34], congenital heart disease [35, 36], mild cognitive impairment [37], coronary heart disease [38] and nasopharyngeal carcinoma [39].

Herbal safety

Certain Chinese medicine herbs are toxic and others may have adverse effects when used improperly [16]. A condition known as the ginseng abuse syndrome is characterized by heart palpitations, heaviness in the chest, high blood pressure, dizziness, insomnia, agitation, restlessness, nausea, vomiting, abdominal pain and/or bloating, diarrhea, possible upper digestive tract bleeding, edema, and red skin rash [40]. Most of these reported adverse effects are common manifestations of Qi-excess and Qi-stasis. While all clinical trials should document adverse effects, only one trial did do so [41].

Re-examination of equivocal ginseng trial results

To exemplify our framework of experimental study design, we searched and analyzed randomized controlled trials of ginseng in PubMed. The inclusion criteria were single herb ginseng trials with a sample size of ≥20. We selected trials of single herb ginseng because the majority of the trials belonged to this category. Nineteen clinical trials were selected for analysis according to the inclusion criteria (Table 1) [4246]. Most of the trials were considered good based on a trial quality evaluation scale [47].

Table 1 Summary of results from single herb ginseng clinical trials

Research topic

Out of the 19 trials, nine had negative results, ten had positive results, and none targeted ginseng's efficacy on Qi-deficiency syndromes.


Both healthy and unhealthy participants were evaluated for the effects of ginseng. Seven out of the nine trials with negative results involved healthy participants, whereas eight out of the ten studies with positive results had participants with Qi-deficiency manifested by cancer, impotence and pulmonary disease. Ellis et al. [48] investigated the time-dependent effects of P. ginseng on the quality of life in a healthy young adult population. In this case, the participants had marginal Qi-deficiency as young adults are at the stage of 'gradual filling of Qi and Xue' [9] according to Chinese medicine theory.

Herbal species/safety

The species of ginseng may be a confounding factor in the interpretation of trial results, which is illustrated by four trials as follows (Table 1).

Stavro et al. [40] enrolled 52 hypertensive participants to evaluate the long-term effects of P. quinquefolius on blood pressure [49]. Long-term use of ginseng was reported to be associated with the development of hypertension, which was refuted by Stavro et al. In Chinese medicine practice, however, P. quinquefolius, unlike its cousin P. ginseng, is in fact used to treat hypertension in some cases.

Wiklund et al. [50] reported a trial in which 384 symptomatic postmenopausal women were assessed for the effects of P. ginseng on the quality of life and physiological parameters. Postmenopausal symptoms such as hot flashes are often regarded as Shen (kidney) Yin-deficiency [51] and are treated with P. quinquefolius rather than P. ginseng. Moreover, the use of P. ginseng in this study was contraindicated and might have produced adverse effects.

Cicero et al. [52] studied 20 elderly hypertensive and digitalized patients treated with Acanthopanax senticosus (Siberian ginseng) which is a mild Qi-tonic for an unspecific feeling of fatigue, a sign of Qi-deficiency [53]. Hypertension is manifested in five syndromes [11], of which Qi-deficiency is only a minor one. The positive results from this trial were due to the fact that A. senticosus, an alternative Qi-tonic, was used [16].

Liang et al. [54] found that P. notoginseng improved endurance time to exhaustion and lowered mean blood pressure in 29 untrained young adults during an endurance exercise. P. notoginseng is another important ginseng species classified as homeostatic medicine to arrest bleeding and removes stagnant Xue.


Our analysis of 19 randomized controlled clinical trials of single herb ginseng shows that all the trials with both negative and positive results confirm the specific effects of ginseng indicated by Chinese medicine theory. Therefore, study designs guided by Chinese medicine theory are necessary to validate and improve future randomized controlled clinical trials in Chinese medicine.


  1. World Health Organization. []

  2. Hesketh T, Zhu WX: Health in China. Traditional Chinese medicine: one country, two systems. Bmj. 1997, 315: 115-117.

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  3. Ernst E: The role of complementary and alternative medicine. Bmj. 2000, 321: 1133-1135. 10.1136/bmj.321.7269.1133.

    Article  PubMed Central  CAS  PubMed  Google Scholar 

  4. Normile D: Asian medicine. The new face of traditional Chinese medicine. Science. 2003, 299: 188-190. 10.1126/science.299.5604.188.

    Article  CAS  PubMed  Google Scholar 

  5. Xiang YZ, Shang HC, Gao XM, Zhang BL: A comparison of the ancient use of ginseng in traditional Chinese medicine with modern pharmacological experiments and clinical trials. Phytother Res. 2008, 22: 851-858. 10.1002/ptr.2384.

    Article  PubMed  Google Scholar 

  6. Vogler BK, Pittler MH, Ernst E: The efficacy of ginseng. A systematic review of randomised clinical trials. Eur J Clin Pharmacol. 1999, 55: 567-575. 10.1007/s002280050674.

    Article  CAS  PubMed  Google Scholar 

  7. Shea JL: Applying evidence-based medicine to traditional chinese medicine: debate and strategy. J Altern Complement Med. 2006, 12: 255-263. 10.1089/acm.2006.12.255.

    Article  PubMed  Google Scholar 

  8. De Smet PA: Herbal remedies. N Engl J Med. 2002, 347: 2046-2056. 10.1056/NEJMra020398.

    Article  PubMed  Google Scholar 

  9. Li D: Basic Theory of Traditional Chinese Medicine. 2006, Beijing: People's Medical Publishing House, 1

    Google Scholar 

  10. Ji S, Cheng Z: Traditional Chinese Diagnostics. 2005, Beijing: People's Medical Publishing House, 1

    Google Scholar 

  11. Zou ZD, Liu N, Guo P, Guo LY, Sun Y, Shi J, Wang L: [Analysis on clinical treatment in hypertension by traditional Chinese medicine for 10 years in Beijing]. Zhongguo Zhong Yao Za Zhi. 2007, 32: 1569-1572.

    PubMed  Google Scholar 

  12. Xu XY, Liu QR, Chen J: [Clinical observation of Qi deficiency syndrome in 72 patients with chronic obstructive pulmonary disease treated with yiqi mianyi granule]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1996, 16: 81-83.

    PubMed  Google Scholar 

  13. Wang XM, Yu RC, Wang YT: [Study on advanced non-small cell lung cancer patients with Qi deficiency and blood stasis syndrome]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1994, 14: 724-726.

    CAS  PubMed  Google Scholar 

  14. Li J, Zhang MZ, Chen BJ: [Effect of tongguan capsule on post-intervention patients of coronary heart disease with qi-deficiency and blood stasis syndrome]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 2008, 28: 32-35.

    PubMed  Google Scholar 

  15. Liu Q, Liu J, Liu D: Clinical research into ke min yin for treatment of persistent allergic rhinitis in patients with qi deficiency and blood stasis. J Tradit Chin Med. 2003, 23: 106-108.

    PubMed  Google Scholar 

  16. Huang Z: Traditional Chinese Pharmacology. 2006, Beijing: People's Medical Publishing House, 1

    Google Scholar 

  17. Allen JD, McLung J, Nelson AG, Welsch M: Ginseng supplementation does not enhance healthy young adults' peak aerobic exercise performance. J Am Coll Nutr. 1998, 17: 462-466.

    Article  CAS  PubMed  Google Scholar 

  18. Cardinal BJ, Engels HJ: Ginseng does not enhance psychological well-being in healthy, young adults: results of a double-blind, placebo-controlled, randomized clinical trial. J Am Diet Assoc. 2001, 101: 655-660. 10.1016/S0002-8223(01)00165-1.

    Article  CAS  PubMed  Google Scholar 

  19. Engels HJ, Fahlman MM, Wirth JC: Effects of ginseng on secretory IgA, performance, and recovery from interval exercise. Med Sci Sports Exerc. 2003, 35: 690-696. 10.1249/01.MSS.0000058363.23986.D2.

    Article  PubMed  Google Scholar 

  20. Engels HJ, Kolokouri I, Cieslak TJ, Wirth JC: Effects of ginseng supplementation on supramaximal exercise performance and short-term recovery. J Strength Cond Res. 2001, 15: 290-295. 10.1519/1533-4287(2001)015<0290:EOGSOS>2.0.CO;2.

    CAS  PubMed  Google Scholar 

  21. Engels HJ, Wirth JC: No ergogenic effects of ginseng (Panax ginseng C.A. Meyer) during graded maximal aerobic exercise. J Am Diet Assoc. 1997, 97: 1110-1115. 10.1016/S0002-8223(97)00271-X.

    Article  CAS  PubMed  Google Scholar 

  22. Gross D, Shenkman Z, Bleiberg B, Dayan M, Gittelson M, Efrat R: Ginseng improves pulmonary functions and exercise capacity in patients with COPD. Monaldi Arch Chest Dis. 2002, 57: 242-246.

    CAS  PubMed  Google Scholar 

  23. Kim JH, Park CY, Lee SJ: Effects of sun ginseng on subjective quality of life in cancer patients: a double-blind, placebo-controlled pilot trial. J Clin Pharm Ther. 2006, 31: 331-334. 10.1111/j.1365-2710.2006.00740.x.

    Article  PubMed  Google Scholar 

  24. McElhaney JE, Gravenstein S, Cole SK, Davidson E, O'Neill D, Petitjean S, Rumble B, Shan JJ: A placebo-controlled trial of a proprietary extract of North American ginseng (CVT-E002) to prevent acute respiratory illness in institutionalized older adults. J Am Geriatr Soc. 2004, 52: 13-19. 10.1111/j.1532-5415.2004.52004.x.

    Article  PubMed  Google Scholar 

  25. Predy GN, Goel V, Lovlin R, Donner A, Stitt L, Basu TK: Efficacy of an extract of North American ginseng containing poly-furanosyl-pyranosyl-saccharides for preventing upper respiratory tract infections: a randomized controlled trial. Cmaj. 2005, 173: 1043-1048.

    Article  PubMed Central  PubMed  Google Scholar 

  26. Sievenpiper JL, Arnason JT, Leiter LA, Vuksan V: Decreasing, null and increasing effects of eight popular types of ginseng on acute postprandial glycemic indices in healthy humans: the role of ginsenosides. J Am Coll Nutr. 2004, 23: 248-258.

    Article  CAS  PubMed  Google Scholar 

  27. Sievenpiper JL, Arnason JT, Leiter LA, Vuksan V: Null and opposing effects of Asian ginseng (Panax ginseng C.A. Meyer) on acute glycemia: results of two acute dose escalation studies. J Am Coll Nutr. 2003, 22: 524-532.

    Article  PubMed  Google Scholar 

  28. Sievenpiper JL, Sung MK, Di Buono M, Seung-Lee K, Nam KY, Arnason JT, Leiter LA, Vuksan V: Korean red ginseng rootlets decrease acute postprandial glycemia: results from sequential preparation- and dose-finding studies. J Am Coll Nutr. 2006, 25: 100-107.

    Article  CAS  PubMed  Google Scholar 

  29. Sievenpiper JL, Arnason JT, Leiter LA, Vuksan V: Variable effects of American ginseng: a batch of American ginseng (Panax quinquefolius L.) with a depressed ginsenoside profile does not affect postprandial glycemia. Eur J Clin Nutr. 2003, 57: 243-248. 10.1038/sj.ejcn.1601550.

    Article  CAS  PubMed  Google Scholar 

  30. Oka H, Yamamoto S, Kuroki T, Harihara S, Marumo T, Kim SR, Monna T, Kobayashi K, Tango T: Prospective study of chemoprevention of hepatocellular carcinoma with Sho-saiko-to (TJ-9). Cancer. 1995, 76: 743-749. 10.1002/1097-0142(19950901)76:5<743::AID-CNCR2820760506>3.0.CO;2-V.

    Article  CAS  PubMed  Google Scholar 

  31. Sheehan MP, Atherton DJ: One-year follow up of children treated with Chinese medicinal herbs for atopic eczema. Br J Dermatol. 1994, 130: 488-493. 10.1111/j.1365-2133.1994.tb03383.x.

    Article  CAS  PubMed  Google Scholar 

  32. Sheehan MP, Atherton DJ: A controlled trial of traditional Chinese medicinal plants in widespread non-exudative atopic eczema. Br J Dermatol. 1992, 126: 179-184. 10.1111/j.1365-2133.1992.tb07817.x.

    Article  CAS  PubMed  Google Scholar 

  33. Xue T, Roy R: Studying traditional Chinese medicine. Science. 2003, 300: 740-741. 10.1126/science.300.5620.740.

    Article  CAS  PubMed  Google Scholar 

  34. Wang W, Niu RJ: [Effects of sheng mai injection on thoracoabdominal motion]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1993, 13: 91-93.

    CAS  PubMed  Google Scholar 

  35. Ding DZ, Shen TK, Cui YZ: [Effects of red ginseng on the congestive heart failure and its mechanism]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1995, 15: 325-327.

    CAS  PubMed  Google Scholar 

  36. Xia ZY, Liu XY, Zhan LY, He YH, Luo T, Xia Z: Ginsenosides compound (shen-fu) attenuates gastrointestinal injury and inhibits inflammatory response after cardiopulmonary bypass in patients with congenital heart disease. J Thorac Cardiovasc Surg. 2005, 130: 258-264. 10.1016/j.jtcvs.2005.02.046.

    Article  CAS  PubMed  Google Scholar 

  37. Tian JZ, Zhu AH, Zhong J: [A follow-up study on a randomized, single-blind control of King's Brain pills in treatment of memory disorder in elderly people with MCI in a Beijing community]. Zhongguo Zhong Yao Za Zhi. 2003, 28: 987-991.

    PubMed  Google Scholar 

  38. Hu JX, Jia GX, Yan ZR: [Clinical and experimental study of shenshao tongguan pian in treating angina pectoris of coronary heart disease]. Zhong Xi Yi Jie He Za Zhi. 1990, 10: 596-599.

    CAS  PubMed  Google Scholar 

  39. Xie FY, Zeng ZF, Huang HY: [Clinical observation on nasopharyngeal carcinoma treated with combined therapy of radiotherapy and ginseng polysaccharide injection]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 2001, 21: 332-334.

    CAS  PubMed  Google Scholar 

  40. Siegel RK: Ginseng abuse syndrome. Problems with the panacea. Jama. 1979, 241: 1614-1615. 10.1001/jama.241.15.1614.

    Article  CAS  PubMed  Google Scholar 

  41. Scaglione F, Cattaneo G, Alessandria M, Cogo R: Efficacy and safety of the standardised Ginseng extract G115 for potentiating vaccination against the influenza syndrome and protection against the common cold [corrected]. Drugs Exp Clin Res. 1996, 22: 65-72.

    CAS  PubMed  Google Scholar 

  42. Caron MF, Hotsko AL, Robertson S, Mandybur L, Kluger J, White CM: Electrocardiographic and hemodynamic effects of Panax ginseng. Ann Pharmacother. 2002, 36: 758-763. 10.1345/aph.1A411.

    Article  PubMed  Google Scholar 

  43. Dowling EA, Redondo DR, Branch JD, Jones S, McNabb G, Williams MH: Effect of Eleutherococcus senticosus on submaximal and maximal exercise performance. Med Sci Sports Exerc. 1996, 28: 482-489.

    Article  CAS  PubMed  Google Scholar 

  44. de Andrade E, de Mesquita AA, Claro Jde A, de Andrade PM, Ortiz V, Paranhos M, Srougi M: Study of the efficacy of Korean Red Ginseng in the treatment of erectile dysfunction. Asian J Androl. 2007, 9: 241-244. 10.1111/j.1745-7262.2007.00210.x.

    Article  PubMed  Google Scholar 

  45. Hong B, Ji YH, Hong JH, Nam KY, Ahn TY: A double-blind crossover study evaluating the efficacy of korean red ginseng in patients with erectile dysfunction: a preliminary report. J Urol. 2002, 168: 2070-2073. 10.1016/S0022-5347(05)64298-X.

    Article  CAS  PubMed  Google Scholar 

  46. McElhaney JE, Goel V, Toane B, Hooten J, Shan JJ: Efficacy of COLD-fX in the prevention of respiratory symptoms in community-dwelling adults: a randomized, double-blinded, placebo controlled trial. J Altern Complement Med. 2006, 12: 153-157. 10.1089/acm.2006.12.153.

    Article  PubMed  Google Scholar 

  47. Jadad AR, Moore RA, Carroll D, Jenkinson C, Reynolds DJ, Gavaghan DJ, McQuay HJ: Assessing the quality of reports of randomized clinical trials: is blinding necessary?. Control Clin Trials. 1996, 17: 1-12. 10.1016/0197-2456(95)00134-4.

    Article  CAS  PubMed  Google Scholar 

  48. Ellis JM, Reddy P: Effects of Panax ginseng on quality of life. Ann Pharmacother. 2002, 36: 375-379. 10.1345/aph.1A245.

    Article  PubMed  Google Scholar 

  49. Stavro PM, Woo M, Leiter LA, Heim TF, Sievenpiper JL, Vuksan V: Long-term intake of North American ginseng has no effect on 24-hour blood pressure and renal function. Hypertension. 2006, 47: 791-796. 10.1161/01.HYP.0000205150.43169.2c.

    Article  CAS  PubMed  Google Scholar 

  50. Wiklund IK, Mattsson LA, Lindgren R, Limoni C: Effects of a standardized ginseng extract on quality of life and physiological parameters in symptomatic postmenopausal women: a double-blind, placebo-controlled trial. Swedish Alternative Medicine Group. Int J Clin Pharmacol Res. 1999, 19: 89-99.

    CAS  PubMed  Google Scholar 

  51. Zell B, Hirata J, Marcus A, Ettinger B, Pressman A, Ettinger KM: Diagnosis of symptomatic postmenopausal women by traditional Chinese medicine practitioners. Menopause. 2000, 7: 129-134. 10.1097/00042192-200007020-00010.

    Article  CAS  PubMed  Google Scholar 

  52. Cicero AF, Derosa G, Brillante R, Bernardi R, Nascetti S, Gaddi A: Effects of Siberian ginseng (Eleutherococcus senticosus maxim.) on elderly quality of life: a randomized clinical trial. Arch Gerontol Geriatr Suppl. 2004, 69-73. 10.1016/j.archger.2004.04.012.

    Google Scholar 

  53. Yin H: Basic Theory of Traditional Chinese Medicine. 1991, Shanghai: Shanghai Scientific and Technical Publishers, 1

    Google Scholar 

  54. Liang MT, Podolka TD, Chuang WJ: Panax notoginseng supplementation enhances physical performance during endurance exercise. J Strength Cond Res. 2005, 19: 108-114.

    Article  PubMed  Google Scholar 

Download references


We are grateful to the anonymous reviewers for their critical comments on this manuscript.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Jian Yan.

Additional information

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

JY conceived the idea of the manuscript. VFE modified the idea and edited the manuscript. YXH and YJ collected references and participated in the discussions. WKG helped draft the manuscript. JY finalized the manuscript. All authors read and approved the final version of the manuscript.

Authors’ original submitted files for images

Below are the links to the authors’ original submitted files for images.

Authors’ original file for figure 1

Rights and permissions

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Reprints and Permissions

About this article

Cite this article

Yan, J., Engle, V.F., He, Y. et al. Study designs of randomized controlled trials not based on Chinese medicine theory are improper. Chin Med 4, 3 (2009).

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI:


  • Chinese Medicine
  • Ginsenosides
  • Herbal Formula
  • Persistent Allergic Rhinitis
  • Acanthopanax Senticosus