In the West, traditional Chinese medicine is often considered alternative medicine; however, in mainland China and Taiwan, TCM is widely considered to be an integral part of the health care system. The term "TCM" is sometimes used specifically within the field of modern Chinese medicine to refer to the standardized set of theories and practices introduced in the mid-20th century under the government of Mao, as distinguished from related traditional theories and practices preserved by people in Taiwan, Hong Kong and by the overseas Chinese. The more general sense is meant in this article.

TCM developed as a form of noninvasive therapeutic intervention (also described as folk medicine or traditional medicine) rooted in ancient belief systems, including traditional religious concepts. Chinese medical practitioners before the 19th century relied on observation, trial and error, which incorporated certain mystical concepts. Like their Western counterparts, doctors of TCM had a limited understanding of infection, which predated the discovery of bacteria, viruses (germ theory of disease) and an understanding of cellular structures and organic chemistry. Instead they relied mainly on observation and description on the nature of infections for creating remedies. Based on theories formulated through three millennia of observation and practical experience, a system of procedure was formed as to guide a TCM practitioner in courses of treatment and diagnosis.

Unlike other forms of traditional medicine which have largely become extinct, traditional Chinese medicine continues as a distinct branch of modern medical practice, and within China, it is an important part of the public health care system. In recent decades there has been an effort to integrate the discoveries made by traditional Chinese medicine with the discoveries made by workers in the Western medical traditions. One important component of this work is to use the instrumentation and the methodological tools available via Western medicine to investigate observations made and hypotheses raised by the Chinese tradition.

That this effort has occurred is surprising to many for a number of reasons. In most of the world, indigenous medical practices have been supplanted by practices brought from the West, while in Chinese societies, this has not occurred and shows no sign of occurring. Furthermore, many have found it peculiar that Chinese medicine remains a distinct branch of medicine separate from Western medicine, while the same has not happened with other intellectual fields. There is, for example, no longer a distinct branch of Chinese physics or Chinese biology.

TCM is used by some to treat the side effects of chemotherapy, treating the cravings and withdrawal symptoms of drug addicts and treating a variety of chronic conditions that conventional medicine is claimed to be sometimes ineffective in treating. It has also been used to treat antibiotic-resistant infection.

A report issued by the Victorian state government in Australia describes TCM education in China:

Graduates from TCM university courses are able to diagnose in Western medical terms, prescribe Western pharmaceuticals, and undertake minor surgical procedures. In effect, they practise TCM as a specialty within the broader organisation of Chinese health care. 
In other countries it is not necessarily the case that traditional Chinese and Western medicine are practiced concurrently by the same practitioner. TCM education in Australia, for example, does not qualify a practitioner to prescribe scheduled pharmaceuticals, nor to undertake surgical procedures or diagnose in Western medical terms.

TCM theory
The foundation principles of Chinese medicine are not necessarily uniform, and are based on several schools of thought. Received TCM can be shown to be most influenced by Taoism, Buddhism, and Neo-Confucianism.

For over 3000 years (1200 BC - present), Chinese academics of various schools have focused on the observable natural laws of the universe and their implications for the practical characterisation of humanity's place in the universe. In the I Ching and other[citation needed] Chinese literary and philosophical classics, they have described some general principles and their applications to health and healing:

There are observable principles of constant change by which the Universe is maintained. Humans are part of the universe and cannot be separated from the universal process of change.
As a result of these apparently inescapable primordial principles, the Universe (and every process therein) tends to eventually balance itself. Optimum health results from living harmoniously, allowing the spontaneous process of change to bring one closer to balance. If there is no change (stagnation), or too much change (catastrophism), balance is lost and illnesses can result.
Everything is ultimately interconnected. Always use a holistic ("systemic" or "system-wide") approach when addressing imbalances.

Model of the body
The following text needs to be harmonized with text in the article TCM model of the body
Main article: TCM model of the body
Traditional Chinese medicine is largely based on the philosophical concept that the human body is a small universe with a set of complete and sophisticated interconnected systems, and that those systems usually work in balance to maintain the healthy function of the human body. The balance of yin and yang is considered with respect to qi ("breath", "life force", or "spiritual energy"), blood, jing ("kidney essence" or "semen"), other bodily fluids, the (Five elements, emotions, and the soul or spirit (shen). TCM has a unique model of the body, notably concerned with the meridian system. Unlike the Western anatomical model which divides the physical body into parts, the Chinese model is more concerned with function. Thus, the TCM Spleen is not a specific piece of flesh, but an aspect of function related to transformation and transportation within the body, and of the mental functions of thinking and studying.

There are significant regional and philosophical differences between practitioners and schools which in turn can lead to differences in practice and theory.

Macro approach to disease
Traditional Chinese medicine has a "macro" or holistic view of disease. For example, one modern interpretation is that well-balanced human bodies can resist most everyday bacteria and viruses, which are ubiquitous and quickly changing. Infection, while having a proximal cause of a microorganism, would have an underlying cause of an imbalance of some kind. The traditional treatment would target the imbalance, not the infectious organism.[citation needed]

A practitioner might give very different herbal prescriptions to patients affected by the same type of infection, because the different symptoms reported by the patients would indicate a different type of imbalance, in a traditional diagnostic system.

Western medicine treats infections by targeting the microorganisms directly, whether preventively (through sterilization of instruments, handwashing, and covering bandages), with antibiotics, or making use of the immune system through vaccines. Conventional medicine does recognize the importance of nutrition and exercise and reducing stress in maintaining a healthy immune system (and thus preventing infection). It also faces problems with antibiotic resistance caused by overuse of chemical agents and the high mutation rate of microorganisms. Pharmaceutical treatments also sometimes have side effects, the most severe of which are seen in regimens used to treat otherwise fatal illnesses, such as chemotherapy and radiotherapy for cancer, and antiretroviral drugs for HIV/AIDS.

The holistic approach of traditional Chinese medicine makes all practitioners generalists. Western medicine has general practitioners who dispense primary care, but increasing reliance is placed on specialists who have expertise in treating only certain types of diseases. Primary care physicians often refer patients to specialists. Emergency departments are located in large hospitals where many specialists are available.

Diagnostics
Following the macro philosophy of disease, traditional Chinese diagnostics are based on overall observation of human symptoms rather than "micro" level laboratory tests. There are four types of TCM diagnostic methods: observe (望 wàng), hear and smell (聞 wén), ask about background (問 wèn) and read the pulse (切 qiè).[citation needed]

Systems of diagnosis include:

Yin or Yang
Five elements
Eight principles
Zang Fu theory
Meridian (Chinese medicine)
Six levels
Four stages
Three jiaos
Modern practitioners in China often use a traditional system in combination with Western methods.

Traditional Chinese medicine is considered to require considerable diagnostic skill. This often depends on the ability to observe what are described as subtle differences. This may be contrasted with a straightforward laboratory test which indicates an unambiguous cause. A training period of years or decades is said to be necessary for TCM practitioners to understand the full complexity of symptoms and dynamic balances. According to one Chinese saying, A good (TCM) doctor is also qualified to be a good prime minister in a country