Topic summary

Revisiting: Completing a dose with a second syringe, and the dead-volume arithmetic

Practice › Administration subcutaneous injection aseptic technique needle gauge & length injection site reaction Closed

This is a generated summary. It shows the 5 most-liked posts from a topic of 21, 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.

e.dalgleishTL3Regular22 Nov 2024#1

Revisiting: Completing a dose with a second syringe, and the dead-volume arithmetic Writing it up because I had to work it out twice and would rather nobody else did.

I have read the maintained page on this and I still have a gap, so I am asking rather than guessing.

Context: tirzepatide, 23 weeks in, currently at a dose I reached by the standard four-week steps. Everything below is my own record rather than anything a clinician told me.

The specific question is the one in the title. What I have already checked: the labelling summary on the relevant documentation page, the two most-linked topics in this subcategory, and my own notes from the last 6 weeks. What I could not find is whether the answer changes at higher doses or whether it is the same arithmetic throughout.

If the answer is "it depends", I would rather know what it depends on than be given a number.

58 likes 20mo

m.ivaturiTL2 Moderator19 Feb 2025#6

A site rotation scheme that actually works: abdomen, outer thigh, back of arm, outer hip. Rotate through them in order, move a minimum 2 cm between consecutive sites, note the site with each dose. If a local reaction appears you have the history. If you rotate properly you will not get lipohypertrophy from overuse of one area.

22 likes 17mo

c.niemelTL3Regular11 Apr 2025 · edited#10

post #9 answers the question as asked. The question underneath it is different.

Injection discomfort: comes from needle gauge (finer = less discomfort), volume (smaller = less discomfort), temperature (room temperature or warmed is less uncomfortable than cold), and technique (smooth, purposeful injection is less uncomfortable than hesitant). All four are under your control.

30 likes 16mo

c.vermeulenTL2 Moderator8 Jun 2025#15

Bleeding at the injection site: normal and usually minimal. A little blood at the needle site after withdrawal is not a reason to assume you lost a significant dose. The needle passed through tissue and there is a small amount of bleeding in the tract.

24 likes 14mo

preregisteredTL3Research methods31 Jul 2025#20

Angle of injection: 90 degrees into pinched tissue ensures subcutaneous placement. It is not always necessary and shallower angles can work, but 90 degrees into a small pinch is the safest technique to learn first.

18 likes 12mo

Read the full topic (21 posts)

This topic was referenced in

Pinch or no pinch, and how needle length changes the answer — the long versionPractice › Administration · 79 replies

This topic was closed 90 days after the last reply. Closing is automatic for quiet topics so that a settled answer does not collect new questions underneath it. If you have a follow-up, open a new topic and link back to this one — that keeps both readable and gives your question its own title.

Moved from Reconstitution by dr_okonkwo. 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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