This page is quoted from NCCIH website to give you an idea what is understood about acupuncture from science aspect.
The National Center for Complementary and Integrative Health (NCCIH) is the Federal Government’s lead agency for scientific research on the diverse medical and health care systems, practices, and products that are not generally considered part of conventional medicine. NCCIH was formerly known as the National Center for Complementary and Alternative Medicine.
How much do we know about acupuncture?
There have been extensive studies conducted on acupuncture, especially for back and neck pain, osteoarthritis/knee pain, and headache. However, researchers are only beginning to understand whether acupuncture can be helpful for various health conditions.
What the Science Says About the Effectiveness of Acupuncture
Results from a number of studies suggest that acupuncture may help ease types of pain that are often chronic such as low-back pain, neck pain, and osteoarthritis/knee pain. It also may help reduce the frequency of tension headaches and prevent migraine headaches. Therefore, acupuncture appears to be a reasonable option for people with chronic pain to consider. However, clinical practice guidelines are inconsistent in recommendations about acupuncture.
The effects of acupuncture on the brain and body and how best to measure them are only beginning to be understood. Current evidence suggests that many factors—like expectation and belief—that are unrelated to acupuncture needling may play important roles in the beneficial effects of acupuncture on pain. For more information, please see on their website.
For low back pain: Clinical practice guidelines issued by the American Pain Society and the American College of Physicians in 2007 recommend acupuncture as one of several nondrug approaches physicians should consider when patients with chronic low-back pain do not respond to self-care (practices that people can do by themselves, such as remaining active, applying heat, and taking pain-relieving medications).
A 2017 evaluation of the research on acupuncture found evidence that it has a small beneficial effect on acute low-back pain and a moderate beneficial effect on chronic low-back pain. Based on this evaluation, a 2017 clinical practice guideline (guidance for health care providers) from the American College of Physicians (ACP) included acupuncture among the nondrug treatment options for management of both acute and chronic low-back pain.
For neck pain: A large German study with more than 14,000 participants evaluated adding acupuncture to usual care for neck pain. The researchers found that participants reported greater pain relief than those who didn’t receive it; the researchers didn’t test actual acupuncture against simulated acupuncture.