Devices · Syringes & needles · continued

A ten-fold dose error caught before injection posts 61–90

Devices › Syringes & needles needle gauge & length worked example syringe units dead volume Closed

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

p.iyer_pharmdTL3Pharmacist7 Jul 2025#61

f.demir, post #52: Silicone coating on the barrel affects how smoothly the plunger moves and how a very slow injection feels. It is one reason two syringes at the same specification are not identical to use. That distinction has done more work for me than anything else in this category. Go to post

On post #59 — agreed on the reasoning, with one qualification.

Needle gauge: smaller numbers (30G) are finer and less painful. Larger numbers (25G) are courser. For subcutaneous injection, 27-30G is typical. Finer needles take longer to draw up but hurt less.

32 likes in reply to #52 13mo

n.okwuosaTL29 Jul 2025#62

Picking up post #59: that is the part I would want checked first.

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.

17 likes 13mo

hana.satoTL4 Moderator11 Jul 2025#63

Graduation spacing is worth checking before you buy rather than after. Some 1 mL barrels are marked every two units and some every one, and that changes what doses you can read.

That is what I would do. It may not be what is correct.

3 likes 13mo

a.aguirreTL213 Jul 2025#64

Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.

0 likes 13mo

k.otieno_statsTL315 Jul 2025#65

Collapsed as off-topic by two members at trust level 3 or above

Worth separating two things that post #63 runs together.

Small methodological point on ten-fold dose error caught: repeating a measurement is cheap and resolves most of what is being argued about here at no cost to anyone.

n.ibarraTL217 Jul 2025#66

Ten-fold dose error caught looks different depending on whether you are reading the primary literature or the summaries of it, and the difference is not in our favour.

23 likes 12mo

system_suitabilityTL3Analytical chemist18 Jul 2025#67

Insulin syringe graduations: U-100 syringes are marked in units where 100 units = 1 mL. Always confirm your syringe is U-100. Confusion between insulin units and milligrams is the most common syringe error.

6 likes 12mo

z.okonkwoTL220 Jul 2025#68

Appreciated. The plain phrasing does more work here than a longer post would.

1 like 12mo

l.trevinoTL222 Jul 2025#69

Buying a box of the wrong barrel size is the most common regret described in this subcategory, and the reason is nearly always that the dose was decided after the syringes.

Written from notes rather than memory, which is why the numbers are specific.

17 likes 12mo

e.okaforTL224 Jul 2025#70

I have been on both sides of the ten-fold dose error caught argument in this category within eighteen months, which should tell you how strong the evidence for either side is.

7 likes 12mo

h.nwosuTL226 Jul 2025#71

Collapsed as off-topic by two members at trust level 3 or above

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.

That is the version I would defend. It is not the version I started with.

OstrowskiTL2Member28 Jul 2025#72

Everything in post #69 holds. The case it does not cover is the one I have.

Needle gauge: smaller numbers (30G) are finer and less painful. Larger numbers (25G) are courser. For subcutaneous injection, 27-30G is typical. Finer needles take longer to draw up but hurt less.

I have separated what I observed from what I concluded, which does not always happen.

0 likes 12mo

j.silvaTL229 Jul 2025#73

Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error.

2 likes 12mo

ThibodeauTL3Regular31 Jul 2025 · edited#74

Adding the boring version of ten-fold dose error caught, because the interesting version keeps getting posted and the boring one is usually right.

Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.

8 likes 12mo

m.restrepoTL22 Aug 2025#75

h.jansen, post #7: Coming back to post #3, because the follow-up matters more than the original answer. The most useful thing anyone has posted about ten-fold dose error caught in this category was a table of what had been measured and by whom. That is what I would want again. Go to post

Reading rather than contributing, but this is the most useful thread I have found on it.

13 likes in reply to #7 12mo

l.oseiTL24 Aug 2025#76

I read post #72 twice before replying, because I had assumed the opposite.

Drawing air into the vial before withdrawing liquid equalises the pressure and makes the draw easier. It is not required and it is why some people find a full vial harder to draw from than a half-empty one.

27 likes 12mo

a.asanteTL26 Aug 2025#77

Worth separating ten-fold dose error caught as a question about the compound from ten-fold dose error caught as a question about the documentation. They get answered by different people and only one of them is answerable here.

0 likes 12mo

d.bakkerTL27 Aug 2025#78

Small correction to my own earlier position on ten-fold dose error caught. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.

4 likes 12mo

i.beaulieuTL29 Aug 2025#79

Post #78 is right about the mechanism and I think understates the practical bit.

U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.

8 likes 12mo

IMainwaringTL3Regular11 Aug 2025#80

q.zhao_qa, post #34: Worth separating two things that post #32 runs together. 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. Posting it because the silence on this was starting to look like agreement. Go to post

Speaking only to ten-fold dose error caught as I have actually seen it, rather than as it is usually described: the effect is real, it is smaller than the thread suggests, and the variance between people is larger than the effect.

19 likes in reply to #34 12mo

s.roosTL213 Aug 2025#81

Ridgeway, post #4: Post #3 answers the question as asked. The question underneath it is different. Two claims get bundled together under ten-fold dose error caught and they need separating. The descriptive one — this is what was observed — is usually well supported. The causal one — this is why — usually is not. Almost every disagreement in threads like… Go to post

Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.

I would be interested in a counterexample if anyone has one.

19 likes in reply to #4 11mo

desiccant_notesTL2Member14 Aug 2025#82

That is a cleaner way of putting what I was circling around.

8 likes 11mo

a.lindqvistTL216 Aug 2025 · edited#83

I had written a reply contradicting post #81 and deleted it. Here is what survived.

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.

2 likes 11mo

g.valckenaereTL3Regular18 Aug 2025#84

e.dalgleish, post #23: Reading units correctly: look at the marking from the side, not from above or below. The bottom of the plunger tip is the reading. Parallax error (wrong angle) is a source of dosing error. The part I am sure of is shorter than the part I have written. Go to post

The failure mode on ten-fold dose error caught is boring rather than dramatic. It is almost always the step everyone assumes was done correctly because it is too simple to get wrong.

0 likes in reply to #23 11mo

m.ilungaTL220 Aug 2025#85

Post #81 describes the usual case. This is about the unusual one.

The version of ten-fold dose error caught 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.

26 likes 11mo

revision_historyTL3Wiki editor22 Aug 2025#86

Adding the measurement that post #85 says would settle it.

Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.

13 likes 11mo

s.teixeiraTL223 Aug 2025#87

A detachable luer needle plus hub can retain enough volume to matter. Whether it matters to you depends on your dose, and the arithmetic is worth doing once.

Same conclusion as the reply above, reached differently, which is mildly reassuring.

4 likes 11mo

m.ferrandTL1Member25 Aug 2025#88

s.antonsen, post #33: If someone has run ten-fold dose error caught properly I would rather read that than my own reconstruction of it. Posting mine only because the thread has gone quiet. Go to post

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.

Adding the caveat now so it does not have to be extracted later.

0 likes in reply to #33 11mo

t.tullochTL227 Aug 2025#89

Thibodeau, post #74: Adding the boring version of ten-fold dose error caught, because the interesting version keeps getting posted and the boring one is usually right. Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does. Go to post

That is consistent with mine, for whatever one more account is worth.

0 likes in reply to #74 11mo

BBramleyTL3Regular28 Aug 2025#90

h.delgado, post #55: Reading rather than answering, but this is the post I would point somebody at. Go to post

Since ten-fold dose error caught keeps coming up, it should probably be a maintained page rather than a recurring thread. I am happy to draft it if someone with more direct experience will review it.

18 likes in reply to #55 11mo