How large are the acupuncture needles?

Acupuncture needles are 25-50 times thinner than a hypodermic needle. They are so thin that several acupuncture needles can go into the middle of a hypodermic needle. There is little sensitivity to the insertion of acupuncture needles.

While some people feel nothing at all; others experience a brief moment of discomfort as the needle penetrates the skin that can be followed by a mild sensation of cramping, tingling, numbness, traveling warmth, or heaviness. The needles are left in place for twenty to forty minutes. Most people find the experience extremely relaxing and uplifting and even fall asleep for the duration of the treatment.

That being said, some conditions will respond better to a thicker gauge acupuncture needle.  It is common to experience soreness during and after an acupuncture treatment.  It is important to let your acupuncturist know immediately so that they can make you more comfortable.  If you are sensitive to acupuncture or ‘needle-phobic’ your acupuncturist can use thinner needles and be gentler.  Be sure to speak up and let the practitioner know how you are feeling!  More...

Source: Acufinder.com