Pernicious Anaemia Society
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? Intradermal B12 injection

Hi all, I have hypothyroidism and seem to have mucin everywhere so that the only places I can 'pinch an inch' i.e. Pinch up skin is on the top of my hands and the top of my feet.

I have low B12 (don't know yet if it's PA) and have self injected B12 in my abdomen doing my best to make it a subcutaneous injection, but because I cant really pull much skin away (mucin seems to attach it to muscles) I have probably - at least partially -injected intradermally.

Does anyone know if this is acceptable/safe? And If the B12 would be absorbed? I have now noticed reddening over a couple of injection sites. It's not itchy, so I'm wondering if it is staining from the B12. Has anyone experienced this problem, and if so, did the B12 work and did the redness disappear?

Thanks in advance.

6 Replies

Hi Tills62. Hmm...first, some thoughts, which may or may not help...and then your questions...and a couple of suggestions.

It's quite difficult to accidentally perform an intradermal injection - the needle and syringe have to be almost flat against the skin to inject in the intradermal space. In addition, intradermal injections usually result in a wheal or blister like eruption, just under the skin (since the injected material is just under the skin).

Can't be sure but it's more likely that you've performed a shallow SC injection (rather than the usual deep SC injection.

Is intradermal injection of B12 safe?

Injectable B12 is not prescribed for intradermal injection. Is it safe to do this - don't know. One patient information leaflet for cyanocobalamin advised injecting 100mcg (0.1ml) via intraderaml injection to test for advers reaction (but that was only for one particular brand of cyanocobalamin).

There are reasons why it may not be advisable if you are affect by mucin. Mucin can be precipitated (caused by) acetic acid and many B12 preparations contain acetic acid - so if you already have mucin, it's possible that if the B12 you use contains acetic acid, then this might exacerbate mucin production - but no idea by how much or, indeed, if at all.

Would the B12 be absorbed?

Any drug or substance injected intradermally is absorbed, but at a much slower rate than via SC or IM injection. This route is usually used for sensitivity tests, BCG vaccinations or local anaesthetic - because the action of the injected substance is delayed/retarded - but it does take place, albeit at a much slower rate.

However, the presence of mucin (which tends to be thick and sticky) may complicate the picture, with the B12 being 'held' in the mucin (if present), with a further potential delay to absorption. So...absorption will take place - but no idea what the absorption rate will be or how it might differ from that of SC or IM injection.

Here's something about mucin (but excuse me if you already know this 😄):

Mucin is a normal constituent of our tissues. It is a jelly-like material that spontaneously accumulates in hypothyroidism. Mucin grabs onto water and causes swelling... Myx is the Greek word for mucin and edema means swelling. Myxedema was adopted as the medical term for hypothyroidism...The edema or swelling associated with hypothyroidism usually begins around the face, particularly above or below the eyes and along the jaw line. However, the skin on the side of the upper arms may be thickened early in the course of the disease. The swelling associated with hypothyroidism is firm and will eventually spread throughout our bodys connective tissues.

One of the many functions of connective tissue is to help hold our bodies organs and structures together. Connective tissue lines our blood vessels, nervous system, muscles, mucous membranes, the gut, as well as each and every cell in our glands and organs. Abnormal accumulation of mucin in these tissues causes swelling and significantly impairs normal function.

This type of swelling is unique to hypothyroidism. Medical textbooks about hypothyroidism state that myxedema is thyroprival (pertaining to or characterized by hypothyroidism) and pathognomonic (specifically distinctive and diagnostic). Translation: if the thickened skin of myxedema is present, you have hypothyroidism. Normal skin is relatively thin, and you may easily lift it with your thumb and index finger. If you look, youll find a number of people whose skin is almost impossible to lift. This is due to the marked swelling and glue-like infiltration of mucin in the skin and underlying tissues that result from hypothyroidism. Womens skin usually has slightly more subcutaneous fat than men. Hence, their skin tends to be thicker. There are many different degrees of myxedema.

I've noticed reddening over a couple of injection sites...could this be staining from the B12.

Not easy to answer that. It could be, especially if the injection is intradermal or shallow SC - the B12 will be subject to a slower absorption rate (perhaps further slowed by the presence of mucin). If this is the case, the redness will disappear over time as the B12 is gradually absorbed. could be minor inflammation due to the presence of the B12 in the intradermal space - if it's sore, swollen or itchy this is more likely to be the case. If the skin breaks down (unlikely - but something to watch for) you would need to see a doctor.

Given the problems that you're having (you can't be really sure where the B12 is actually going) and that manufactures do not recommend vitamin B12 for intradermal injection (deep SC and IM only) think that I'd have to suggest that this is perhaps not the best way for you to inject - unless you've discussed it with your doctor and they agree that it okay for,you do do this. If it was me, I wouldn't want to inject B12 intradermally (or risk doing so).

Also - it's possible to do a deep SC injection without having to pull up the skin - just a different method (angle the needle at 45% and simply slide in - depth depends on how much subcutaneous you have 😄).

A further might have more success with IM (intramuscular) injections. These go deep into the muscle and you'd avoid the issues that are worrying you at the moment...and the absorption rate wouldn't be affected by being slowed or retarded. It's really not more difficult that doing an SC injection (once you've done the first one).

Perhaps your GP or nurse at the surgery would show you how to do it?

Anyway...hope this helps...good luck 👍


Thank you so much for your response, Foggyme, I really appreciate it. There is no sign of blistering, and no itching. I have completed the loading doses, so I can wait to see if the redness disappears before having another injection. I think I have probably been giving myself shallow SC injections. Thanks again.

1 like

No problem. Try IM injections 😉. Good luck.


I don't feel brave enough to do that yet :-( maybe one day!

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I inject deep S.C and sometimes get a Barbie pink mark. I think it's just where a little B12 bubbles up to just under the skin. The mark fades over a few days as the B12 gets absorbed and doesn't seem to make the jab any less effective for me.

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Thank you for that, topazrat. That makes me feel a lot better. Mine seem to have faded a little today too.


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