What kind of needles are used in acupuncture?
In the US, the only needles legal these days are solid, pre-sterilized, single-use needles that are immediately discarded as medical waste – ie in a ‘sharps’ container identical to those used in hospitals – and delivered via very controlled methods to a designated site where they are incinerated along with all the other needles, lancets and ‘sharps’ from medical facilities.
Until a few years ago it was legal (although discouraged) to re-sterilize them yourself if you used an autoclave machine (compressed steam-heat, known to kill all organisms and produce complete sterility if used correctly). These are effective enough to still be used in hospitals for some equipment; but user error, device failure, and the impossibility of preventing and monitoring those things made its use risky enough in the acupuncture field that this method is no longer allowed. In China, I believe this method is still allowed, and it doesn’t always work out awesomely, for the above stated reasons – there remain a handful of recently documented cases of transmitted disease definitively traced to re-use of acupuncture needles there. There is a lot to be said for simplifying the process at the lowest common denominator of risk; we’ve admitted the value of that pretty recently in Western healthcare too.
If what you mean is more along the lines of: how big/long/thick are the needles and/or what are they made of?… the answers are as follows:
The needles vary in length and thickness – some can be inches long – although generally they are nowhere near as thick as the ones you’d find yourself on the other end of in a hospital or doctor’s office. An acupuncturist chooses the length and thickness of the needle based upon what he/she wants to achieve, where the needle is to be placed and how much tissue it will have to go through to tap the meridian underneath. I have a ‘standard’ go-to default size of 20×25, meaning a diameter of 0.2 mm and a length of 25mm: a little thicker than a hair, and maybe an inch and a half or so long, including the handle. However, say I want to put needles at the tips of the fingers or in the face – I might want the same thickness, but want less ‘torque’ on the needles which will tend to fall over or move round with all that extra length on such a shallow area… so maybe I’d use a 20×16 – still 0.2 diameter but only 16mm length, for more stability… just as an example. Depending on brand, they can be mixed and matched up to several inch-long needles with greater thickness for use in very dense areas (like the buttocks/hips) or on people with more adipose tissue.
Most needles these days are stainless steel, which is considered a ‘neutral’ metal energetically. Gold is sometimes used and is considered to be particularly tonifying – so its indication would be when the goal is to correct deficiencies. There are also silver needles, considered very dispersing – so help with stagnant conditions especially involving heat – such as fever or inflammation. But practically-speaking, because the precious metals are so much more expensive -and stainless, being neutral, can properly be used for any condition – most acupuncturists stick with that, as far as I know – hard-core classic purists excepted, I’m sure!