Are there side-effects or risks from herbal medicine?

An Australian survey of 1100 TCM practitioners listed adverse events encountered per practitioner year (py). Those due to Chinese herbal medicine include allergic reactions and toxicity. Most serious adverse effects from Chinese herbal medicine were severe gastrointestinal symptoms (1 per 67 pys), significant skin reaction (1 per 77 pys), and fainting or dizziness (1 per 71 pys). Although the data may underestimate frequency, it seems reasonable to conclude that there are significantly fewer adverse reactions in TCM than in Western medicine1,7.

Is Chinese herb medicine different than other herb medicine?

Most herbal medicine therapies and the theory of their application developed within particular geographic and cultural contexts. Chinese herbal medicine (Materia Medica) uses approximately 8,000 materials. Although most are plant parts, there are also some insect and animal products, and minerals. A typical Chinese herb pharmacy might have between 100 and 500 of these on hand.

Although each “herb” has specific properties in herbal medicine, most are used in combinations called formulas. There are hundreds of standard formulas for categorized conditions. However, TCM theory says that each individual must be treated according to their unique combination of symptoms. Also, many herbs require a balance between the desired effect and the other effects. For example, we might use a cool herb for stomach heat; if the stomach is weak, the coldness might be harmful so we would add another herb to strengthen the stomach at the same time. Thus, the TCM herbalist customizes a formula for an individual, unlike some western herbal therapies in which a single herb or herb extract is used alone.

Are Chinese herbal medicines safer or riskier than conventional pharmaceutical drugs?

People tend to notice bad news more when it is about something new than something familiar. For example, most people who drink red wine to improve health don’t stop drinking if they hear that it is dangerous in large amounts. However, Chinese herbal medicine is unfamiliar to most people, so negative news stories may cause people to hesitate, even if the danger is lower than for everyday things such as caffeine, alcohol, saturated fat, vitamin A, etc.

Pharmaceutical drugs provide substantial benefits, but many also have serious adverse drug outcomes or side effects documented in a growing body of evidence. In contrast, herbal medicines have a reputation of being relatively safe. Even though many modern drugs are derived from plants or work in ways similar to plant products, people argue loudly for or against herbal medicine but often without facts. Adverse effects of herbal medicines are indeed a cause for concern. However, the available evidence suggests that herbal medicines are relatively safe1, 3-8. For example, in an 8-month Hong Kong study, adverse events due to Chinese herbal medicine accounted for 0.2% of hospital admissions versus 4.4% due to Western pharmaceuticals2.

Chinese medicine herbs and techniques have been used for centuries with thousands, even millions of patients. Over time, doctors recorded suitable doses, indications, and cautions. Many herb products are prescribed only under strict conditions and with the practitioner staying in close contact with the user. Many herbs can be substituted if an individual person has adverse reactions or intolerance to a particular one.

As a result, Chinese medicine prepared by a qualified professional practitioner is far less risky than many pharmaceutical drugs. The news stories of dangerous effects or ingredients in Chinese medicine tend to be based on the same themes as many sensational news stories – unusual circumstances, famous people, improper or illegal use of the herb.

If there is real evidence that the Canadian public may be at risk from natural health products, Health Canada will issue an Advisory/Warning, or have them removed from sale. Qualified professionals comply with these regulations.


1 Barrett B, D Kiefer and D Rabago. 1999. Assessing the risks and benefits of herbal medicine: an overview of scientific evidence. Alternative Therapies 5(4):40-49.

2 Chan TYK, AYW Chan and JAJH Critchley. 1992. Hospital admissions due to adverse reactions to Chinese herbal medicines. J. Trop. Med. Hyg. 95:296-298.

3Dartnell J, R Anderson, V Chohan et al. 1996. Hospitalisation for adverse events related to drug therapy: incidence, avoidability and costs. Med. J. Aust. 164:659-662.

4 D’Epiro NW. 1997. Herbal medicine: what works, what’s safe. Patient Care. Oct. 15, 1997: 49-68.

5 Ernst E. 2001. A primer of complementary and alternative medicine commonly used by cancer patients. MJA 174:88-92.

6 Farnsworth NR. 1993. Relative safety of herbal medicines. Herbal Gram. 29(suppl.): 36A-36H.

7 Wilson RM, WB Runciman, WR Gibberd, BT Harrison, L Newby and JD Hamilton. 1995. The quality in Australian health care study. Med. J. Aust. 163:458-471.

8 Xu, X.C. (ed.). 1990. Essentials of Traditional Chinese Medicine. Vol. 1, The English-Chinese encyclopedia of practical Traditional Chinese Medicine. Higher Education Press, Beijing.