Topic summary

Second pass at: Gauge and length selection for subcutaneous injection

Devices › Syringes & needles subcutaneous injection syringe units worked example needle gauge & length

This is a generated summary. It shows the 8 most-liked posts from a topic of 59, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.

c.marchettiTL220 Nov 2024#3

Gauge is the outside diameter and higher numbers are thinner. Thinner needles hurt less and draw more slowly, which is the entire trade.

I looked this up rather than remembered it, which is the right order.

26 likes 20mo

MakinenTL2Member24 Dec 2024#12

Needle length for subcutaneous delivery is a question about tissue depth and injection angle together. Short needles at ninety degrees and longer ones at an angle reach comparable depths.

25 likes 19mo

gradient_fileTL2Member5 Jan 2025#16

Narrowing post #13, because the general version has more than one answer.

The most useful thing anyone has posted about Gauge and length selection in this category was a table of what had been measured and by whom. That is what I would want again.

33 likes 19mo

plateau_notesTL2Regular3 Feb 2025 · edited#26

sterile_file, post #4: Post #2 describes the usual case. This is about the unusual one. Needle length: typical lengths for subcutaneous injection are 4-6 mm (short), 8 mm (standard), or 10-12 mm (longer). Longer needles are needed for deeper tissue or if you have abdominal adiposity. That is what I would do. It may not be what is correct. Go to post

Everything in post #24 holds. The case it does not cover is the one I have.

The version of Gauge and length selection that circulates here is a simplification of a simplification. It is not wrong, but it has lost the conditions under which it holds, and those conditions are where the interesting cases live.

20 likes in reply to #4 18mo

s.salgadoTL221 Feb 2025#33

Where I part company with post #31, and it is a narrow parting.

I changed my mind about Gauge and length selection after someone here asked me for the source and I could not produce one. That is worth saying out loud because it is the ordinary way it happens.

20 likes 17mo

t.vasquezTL4 Moderator18 Mar 2025#43

I keep a log for Gauge and length selection specifically because my memory of it turned out to be systematically wrong in one direction. Six weeks of notes cost nothing and settled it.

24 likes 16mo

bac_waterTL2Regular11 Apr 2025#53

Helpful, and short, which on this subject is harder than long.

22 likes 16mo

e.ferreiraTL3Regular18 Apr 2025#56

Reusing a needle blunts it and there is no benefit to offset that. The second injection with the same needle is the one people describe as painful.

31 likes 15mo

Read the full topic (59 posts)

Moved from Pens & autoinjectors by hana.sato. Category placement is not obvious from outside and getting it wrong is expected. This topic will get better answers here. The move is recorded in the public log citing R7.

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