The primary tool of acupuncture is the fine, stainless steel needle. Many patients, when they first experience acupuncture, remark on how painless it is.
The insertion of the needle does produce some sensation, often described as a pinch, or pulling, a heaviness, dullness, tingling and so on. Different styles of acupuncture elicit different sensations. Styles such as Sports Medicine or Dry Needling use a thicker needle to generate more stimulation while trying to loosen up muscles and break up fibrotic knots. Other styles may use thinner needles, and a more gentle method to stimulate pain relief and muscle relaxation.
Infrequently, when a needle is inserted it may stimulate a little nerve ending or nick a small blood vessel. This intense sensation should recede rather quickly, however if it does not then the practitioner can remove the needle and reinsert in such a way that the needling sensation is comfortable.