Topic summary

Filter needles: when they help and what they cost you

Devices › Syringes & needles needle gauge & length subcutaneous injection dead volume

This is a generated summary. It shows the 7 most-liked posts from a topic of 51, 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.

r.mwangiTL2 Moderator13 Dec 2025#4

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

22 likes 7mo

a.wikstromTL2 Moderator1 Jan 2026#16

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.

27 likes 7mo

b.friskTL2 Moderator9 Jan 2026#22

Syringe barrel size: common sizes are 0.3 mL, 0.5 mL, and 1.0 mL. Smaller barrels are more legible for small doses. Larger barrels hold larger volumes. Choose based on your dose.

31 likes 7mo

n.duarteTL2 Moderator14 Jan 2026#26

On post #22 — agreed on the reasoning, with one qualification.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

23 likes 6mo

z.nakamuraTL2 Moderator26 Jan 2026#36

TL4_Halvorsen, post #11: Dead volume: residual liquid in the hub and needle after withdrawal. Typical residual is 0.01 to 0.02 mL for an insulin syringe with a fixed needle. Accounting for it matters if precision matters. Go to post

This follows post #33 rather than contradicting it.

Syringe barrel size: common sizes are 0.3 mL, 0.5 mL, and 1.0 mL. Smaller barrels are more legible for small doses. Larger barrels hold larger volumes. Choose based on your dose.

28 likes in reply to #11 6mo

a.almeidaTL2 Moderator31 Jan 2026#40

c.correia, post #39: Fixed versus detachable needles: insulin syringes usually have fixed needles (no dead volume loss to the hub). Luer-lock syringes use detachable needles (more dead volume). Fixed needles are preferred for small doses. Go to post

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.

21 likes in reply to #39 6mo

outline_firstTL3Wiki editor4 Feb 2026#44

Aspirating before injection: for subcutaneous injection, aspirating (pulling back on the plunger to check for blood) is not necessary and is sometimes discouraged because it is associated with more discomfort. Subcutaneous injection without aspiration is standard practice.

26 likes 6mo

Read the full topic (51 posts)

This topic was referenced in

0.3 mL versus 0.5 mL versus 1 mL barrels: resolution mattersDevices › Syringes & needles · 114 replies
Reading a syringe in poor light, and how to avoid needing toDevices › Syringes & needles · 2 replies
Follow-up: Dead volume across syringe and needle combinationsDevices › Syringes & needles · 98 replies

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