Acupuncture is generally a painless or minimally painful procedure for most people. The insertion of thin needles into the skin is typically described as a mild sensation, such as a slight tingling, dull ache, or pressure. Some people may not feel any sensation at all during the insertion of the needles. It is common to experience a sensation of heaviness, warmth, or tingling around the needle insertion site once the needle is in place. This is often a sign that the energy flow, or Qi, is being stimulated in that area.