Tirz Injection Suddenly Causes Stinging

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Brucester

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One of my rats, after many treatments, has suddenly started showing this: "Very very stingy. Took 4 attempts to inject. Stung so much. đŸ˜©" Does anyone have any idea why? All the other rats using the same batch are completely fine.
 
It seems like hesitation is playing a role for one of your rats right before the shot. They mentioned “4 attempts to inject.”, which points in that direction. The simplest fix is to skip the overthinking, commit, and deliver it quickly, like a small jab. If the stinging were happening afterward, that would point to an injection site reaction (ISR), but the description doesn’t match that pattern.

A common claim is that alcohol left on the skin from the wipe can sting if it hasn’t dried completely. Still, based on what you’ve been told, this looks more like how the injection is being done than something wrong with the product.

ETA: It could also be that the needles have become dull, or that the stopper has been punctured multiple times.
 
Grab yourself a pack of pH testing strips. What are those things called again? Huge doubt if that solution isn't close to neutral on the pH scale.

DIY Hospira? 😳
 
Grogu said:

It seems like hesitation is playing a role for one of your rats right before the shot. They mentioned “4 attempts to inject.”, which points in that direction. The simplest fix is to skip the overthinking, commit, and deliver it quickly, like a small jab. If the stinging were happening afterward, that would point to an injection site reaction (ISR), but the description doesn’t match that pattern.

A common claim is that alcohol left on the skin from the wipe can sting if it hasn’t dried completely. Still, based on what you’ve been told, this looks more like how the injection is being done than something wrong with the product.

ETA: It could also be that the needles have become dull, or that the stopper has been punctured multiple times.
Click to expand...

Grogu said:

It seems like hesitation is playing a role for one of your rats right before the shot. They mentioned “4 attempts to inject.”, which points in that direction. The simplest fix is to skip the overthinking, commit, and deliver it quickly, like a small jab. If the stinging were happening afterward, that would point to an injection site reaction (ISR), but the description doesn’t match that pattern.

A common claim is that alcohol left on the skin from the wipe can sting if it hasn’t dried completely. Still, based on what you’ve been told, this looks more like how the injection is being done than something wrong with the product.

ETA: It could also be that the needles have become dull, or that the stopper has been punctured multiple times.
Click to expand...
Appreciate the response. The rat used to work as a nurse. According to her, the stinging comes from the liquid itself, yet no other rats are reporting the same issue.
 
Sasquatch said:

Grab yourself a pack of pH testing strips. What are those things called again? Huge doubt if that solution isn't close to neutral on the pH scale.

DIY Hospira? 😳
Click to expand...
Hospira isn't available here in the UK. I did consider whether the BAC might be the issue, but only this 1 person is reporting a problem — no one else is.
 
Should the stinging happen as the needle enters the skin, the likely culprit is the alcohol wipe — the alcohol has not evaporated yet, so waiting until it dries should help.

A bigger needle could also be the reason. 29-31 gauge is what most people use, since those are so thin they hardly cause pain. Is it possible the former nurse is reaching for a larger size?

When the sting comes while the drug/peptide goes in, that points to a local tissue reaction against the chemistry of the injected substance rather than an immune response ( too soon ). Certain peptides sting and most do not; bac water with the wrong ph may sting; injecting too shallow — nearer the skin surface, where nerve endings are denser — may sting too. Sensitivity varies across the body, though the subcutaneous fat to the side of the belly button is generally fine. If you want to test the bac water ph, ph test strips are fairly easy to obtain, and even urinalysis strips will read ph.

Should the stinging grow worse afterward, a chemical irritant response remains possible, and an immune response can do it as well — however, a localised injection site reaction from an immune response will normally come with some redness and swelling.
 
I've noticed that the product from certain "providers" causes a stinging sensation, while others don't. Have you started using a different vial lately? I'm usually on the sensitive side, since the other rats here don't have any complaints.
 
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