Like most things I talk about on here, it varies. How far acupuncture needles go in depends on a few things.
Where the needle is being inserted
Bony area = shallow needling
Fatty or muscular area = deeper needling
On the face and neck = shallow needling
What the purpose of the point is
For example, I might choose a point on the arm to release muscular tension or inflammation causing pain in the elbow. I would insert the needle to the depth of the muscle I’m trying to stimulate which could be a centimetre or more. I could also use the same point if you had some eczema or psoriasis in the elbow area. In this case, I would needle superficially just under the skin towards the skin irritation (not directly on it). The depth of needling depends on why I’ve chosen the point and what effect I’m trying to have on that area.
How much tissue there is around the point
We all come in different shapes and sizes, for the chunker areas I will need to go deeper with the needle, for the spindly parts, not so deep
For children, the needles are usually shallow because they are very sensitive! For middle-aged people and the elderly, it depends on the health problem
Type of illness
Traditionally, deeper needling is used with more systemic or chronic health problems and shallower needling for superficial illnesses such as a cold. It’s actually contraindicated to needle deeply if someone has an acute illness as it can ‘drive the illness deeper into the body’.
Deeper needling of the lower back is contraindicated in pregnancy. There’s a lot going on so personally, I use fewer points at shallower depths to avoid over-stimulating mother and baby
Practitioners technique preference
Some practitioners prefer to needle on the deeper side, some prefer more superficial but you will be hard-pressed to find an acupuncturist that only uses deep or shallow needling for the reasons on this list
The difference between shallow and deep needling is in no way massive, I would consider shallow to be just under the skin (a few mm) and deep to be 1.5cm+ with the deepest at about 7cm (the longest needles you can typically buy are 7.5cm)
Every acupuncturist is different in their needling technique and style, find one that suits you personally, and don’t be afraid to ask questions and give feedback about the needles during your treatment.