Because acupuncture needles penetrate the skin, many forms of acupuncture are invasive procedures, and therefore not without risk. Injuries are rare among patients treated by trained practitioners. In most jurisdictions, needles are required by law to be sterile, disposable and used only once; in some places, needles may be reused if they are first resterilized, e.g. in an autoclave.
Certain forms of acupuncture such as the Japanese Tōyōhari and Shōnishin often use non-invasive techniques, in which specially-designed needles are rubbed or pressed against the skin. These methods are common in Japanese pediatric use.
Common, minor adverse events
A survey by Ernst et al. of over 400 patients receiving over 3500 acupuncture treatments found that the most common adverse effects from acupuncture were:
Minor bleeding after removal of the needles, seen in roughly 3% of patients. (Holding a cotton ball for about one minute over the site of puncture is usually sufficient to stop the bleeding.)
Hematoma, seen in about 2% of patients, which manifests as bruises. These usually go away after a few days.
Dizziness, seen in about 1% of patients. Some patients have a conscious or unconscious fear of needles which can produce dizziness and other symptoms of anxiety. Patients are usually treated lying down in order to reduce likelihood of fainting.
The survey concluded: "Acupuncture has adverse effects, like any therapeutic approach. If it is used according to established safety rules and carefully at appropriate anatomic regions, it is a safe treatment method."
Other injury
Other risks of injury from the insertion of acupuncture needles include:
Nerve injury, resulting from the accidental puncture of any nerve.
Brain damage or stroke, which is possible with very deep needling at the base of the skull.
Pneumothorax from deep needling into the lung.
Kidney damage from deep needling in the low back.
Haemopericardium, or puncture of the protective membrane surrounding the heart, which may occur with needling over a sternal foramen (a hole in the breastbone that occurs as the result of a congenital defect.)
Risk of terminating pregnancy with the use of certain acupuncture points that have been shown to stimulate the production of adrenocorticotropic hormone (ACTH) and oxytocin.
The chance of these is very small, and the risk can be further reduced through proper training of acupuncturists. Graduates of medical schools and (in the US) accredited acupuncture schools receive thorough instruction in proper technique so as to avoid these events. (Cf. Cheng, 1987)
Risks from omitting orthodox medical care
Receiving any form of alternative medical care without also receiving orthodox Western medical care can be inherently risky, since undiagnosed disease may go untreated and could worsen. For this reason many acupuncturists and doctors prefer to consider acupuncture a complementary therapy rather than an alternative therapy.
Critics also express concern that unethical or naive practitioners may induce patients to exhaust financial resources by pursuing ineffective treatment. However, many recent public health departments in modern countries have acknowledged the benefits of acupuncture by instituting regulations, ultimately raising the level of medicine practiced in these jurisdictions.
Safety compared with other treatments
Commenting on the relative safety of acupuncture compared with other treatments, the NIH consensus panel stated that "(a)dverse side effects of acupuncture are extremely low and often lower than conventional treatments." They also stated:
"the incidence of adverse effects is substantially lower than that of many drugs or other accepted medical procedures used for the same condition. For example, musculoskeletal conditions, such as fibromyalgia, myofascial pain, and tennis elbow... are conditions for which acupuncture may be beneficial. These painful conditions are often treated with, among other things, anti-inflammatory medications (aspirin, ibuprofen, etc.) or with steroid injections. Both medical interventions have a potential for deleterious side effects but are still widely used and are considered acceptable treatments."
In a Japanese survey of 55,291 acupuncture treatments given over five years by 73 acupuncturists, 99.8% of them were performed with no significant minor adverse effects and zero major adverse incidents (Hitoshi Yamashita, Bac, Hiroshi Tsukayama, BA, Yasuo Tanno, MD, PhD. Kazushi Nishijo, PhD, JAMA). Two combined studies in the UK of 66,229 acupuncture treatments yielded only 134 minor adverse events. (British Medical Journal 2001 Sep 1). The total of 121,520 treatments with acupuncture therapy were given with no major adverse incidents (for comparison, a single such event would have indicated a 0.0008% incidence).
