Angle of injection and whether 90 degrees is always right — the long version Writing it up because I had to work it out twice and would rather nobody else did.
A narrow question about Angle of injection, deliberately narrow, because the broad version has been asked here four times and produced four long threads and no answer.
One question, stated units, stated method, and what I have already ruled out.
The opening post answers the question as asked. The question underneath it is different.
A new needle for each injection is not fussiness. A needle blunts on first use and a blunted needle is the reason the second injection hurts more than the first.
This is the version I would want a new member to read first.
Good question, well framed, and I would like to see it answered properly.
Small correction to my own earlier position on Angle of injection. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
Post #5 is right about the mechanism and I think understates the practical bit.
If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.
The rule of thumb is fine; the edge cases are where it earns its keep.
Air bubbles in a subcutaneous injection: the honest risk assessment is low. Tiny air bubbles in subcutaneous tissue do not behave like an air embolism in a blood vessel. A few air bubbles are not a reason to restart the entire injection.
I am aware this is the third time this month I have made this point.
A genuinely late dose: the labelling generally says that if the next dose is more than a couple of days away, take it as soon as you notice. If the next dose is close, skip it and resume the schedule. The reasoning follows from the long half-life; you are perturbing a slowly moving average.
Fair, and the limits you put on it are the part I will remember.
If you are new and reading this thread for the answer to Angle of injection: the answer is conditional, the conditions are in the third reply, and the rest of the thread is worth skipping.
Confirming post #10 from a second method, which matters more than confirming it from a second person.
If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.
Rotate on a fixed sequence rather than choosing each week. A sequence you follow beats a scheme you improvise, and it produces a record you can read back.
Post #14 is right about the mechanism and I think understates the practical bit.
Drawing up with one needle and injecting with another: a reasonable practice if you have extra needles. Fresh needle for injection reduces tissue drag and can decrease discomfort. Not necessary, but not harmful either.
I am reporting what happened, not recommending it.
If you have to inject at a different time of day than usual, that is a much smaller perturbation than it feels for a weekly compound with a week-long half-life.
This is the first time the answer has come with its own limits attached. Appreciated.
Post #19 is the version of this I will quote in future. One addition.
What I would tell a new member reading about Angle of injection for the first time: the confident posts are not the reliable ones, and the reliable ones are longer.
Answering the question post #19 raises rather than the one it answers.
Pinching a fold is useful for lean tissue and unnecessary elsewhere. The point is to keep the needle out of muscle, and whether you need to depends on the site and on you.
The mechanism is plausible, which is not the same as established.
Subcutaneous injection into abdominal tissue, thigh or upper arm is what the licensed labelling in this class describes, and the published comparisons found the differences in exposure between those sites small.
I am not the right person to answer the follow-up to this.
A note on scope: what I am saying about Angle of injection applies to the case in the first post and I would not extend it further without checking.
The single most common technique error described here is drawing to the wrong graduation because the barrel was read at an angle. Read it straight on, at eye level, every time.
Everything in post #25 holds. The case it does not cover is the one I have.
Alcohol swabbing and letting the site dry is the whole of the preparation for a subcutaneous injection into intact skin. Injecting before it dries is what stings.
Coming back to post #25, because the follow-up matters more than the original answer.
Pinch or no pinch: the decision depends on needle length and on your own anatomy. A longer needle (8 mm and up) reaches subcutaneous tissue easily without a pinch. A shorter needle (4-6 mm) is safer with a gentle pinch. The pinch size matters less than people think; the injection angle matters more.
That has held every time I have looked, which is not the same as always.
Thank you for taking the time. That was more work than a reply usually is.