Wrong size needle

Hi all,

I have recently started B12 injections at home as per my naturopath's instructions. I pick up the B12 and syringes and needles at a local pharmacy.

I just got some new needles, which turned out to be the wrong size for intramuscular injections for my weight. The pharmacist did not check the original prescription. And I did not remember correctly. Okay, so I used, twice now, a 5/8 inch needle when I should be using a 1 inch needle. I noticed 2 times now after shots that the site of the injection burns and itches. This has never happened before. My question: Where is this injection going? Into fat? Is this a subcutaneous injection? I am not getting the full benefit so where does the B12 go? Is this harmful to use the wrong needle size?

Thanks for any help. I am going back to the pharmacy tomorrow for correct needle.

20 Replies

  • Hi!

    I'm surprised the difference between a 5/8ths and 1 inch would show anything. I don't always push my needles all the way in if I come across an extra tough bit! At that length it definitely should be going into muscle, just not as deep.

    Subcutaneous is literally "under the skin" which is less than 1/8th of an inch.

    Let us know how you get on with the full length needles again: very interesting!

  • Hi deniseinmilden,

    Thanks so much for your reply! It turns out when I looked at the paperwork, I need a 1.5 inch needle as I am overweight. I think it went into the fat layer between my skin and my muscle. Have e-mailed my doctor about it. But definitely am not feeling the benefit from the injection. When I massage the area it feels like there is a lump and the site gets gets hot and feels a little burning and itching on the inside around injection site.

    I just don't know if the B12 will disperse and if so how long it will take.

    What a crazy situation!

    Maybe naturopathic doctor can give me more info. I'll keep you posted! Thanks again for reaching out to me. :-)

  • Try a smaller muscle group where you have less fat.

    5/8 is perfect for shoulder. Or if you straighten your arm & rotate your hand so the back of it is facing you, you get a muscle pop up between bicep & tricep called Brachialis. Perfect for 5/8.

    Or why not move to Methyl & do sub-cut?

  • Good suggestions. You sound like a pro regarding the injection sites! I will ask my doctor about sub cutaneous shots as I am using methyl already.

    I appreciate the info and thanks so much for your help!

  • Haha, I'm no pro, but if you really are using Mythyl, I (sadly) know more than your Doc :(

    Are you in UK?

    If you really are using Mythylcobalamin that doesn't need methylation (as the name suggests). Get yourself some insulin syringes. Pinch of belly fat & jab it 90 degrees into what you pinched.

    What strength of Mythyl have you got. 1000mg/ml or 5000/ml?

    Edit, I just read the word Naturopath. These quacks really shouldn't be allowed to give advice, let alone advice that involves injection!!!! I hope you know what you're doing in terms of hygiene & aspiration (although thankfully it is safe to put B12 into a vein).

  • Hi knackersyard,

    I have 2 mg/ml

    and I'm in the U. S.

    Subcutaneous sounds as if I could do it myself. My husband gives me the intramuscular injections.

    I feel so much better with all the sympathetic replies that I have received! And all the good info!

    Much obliged!

  • Hi ndodge

    Glad you didn't take offence to my opinion on "naturopaths". If they advised you to jab Methyl intramuscular with an 1 1/2" needle, I would run a mile.

    OK, so insulin syringes usually come in 1ml & 0.5ml, so you need the 1ml. They come with tiny 25g & 29g x 1/2" needles. If you pinch your belly fat & stick it in at 90deg, you will feel the pinch more than the needle! Easy!!!

  • No offense taken! Why is it a bad idea to inject

    methyl via intramuscular?

    The reason I went to a naturopath was b/c my regular GP only gave Cyano, which did not take away the fatigue and lots of Neuro problems. He did not do loading doses and would not allow me to have more than one a month. The naturopath understands that I need shots once a week. and has methyl, which works great. And she wrote a prescription for me that makes it all less expensive! Say what you will, but she had been a lifesaver to me.

    Thanks for any information about methyl & injecting into muscles or not!


  • When you inject Hydro or Cyano cobalamin into muscle it methylates. It's not necessary to inject Mythyl Into muscle as its already methylated. So why would this quack advise you to stick a 1.5" needle into your muscle, with all the extra risks that entails?

    Subcutaneous is so much easier with no risk of hitting veins & is utterly painless.

    Good luck!

  • Good to know! Thanks so much for your great help. Will check out doing sub cutaneous.

  • Forgive me for muscling-in (no pun intended) but are subcutaneous injection, especially for someone as fat (at the moment) as me, as good as the intramuscular? I'm beginning to be a bit alarmed at the size of needle I'm going to need!

  • You shouldn't need a larger needle for sub-cut. All you need is something to get the dose into the fat tissue. People with a thicker layer of fat would need a longer needle for IM as it has to pass through the subcutaneous layer to get into the muscle.

  • Thanks - but what's worrying me is reading below that subcutaneous can cause abscesses. And is injecting into fat as effective as into muscle?

  • That was deniseinmilden's response to this statement - "the site of the injection burns and itches." I don't think sub-cut is any more likely to cause problems that IM. After all, thousands of diabetics do it several times a day.

    We've recently had a long discussion on IM vs SC. Although no data could be found on B12's behaviour the general consensus seemed to be that IM would probably get the stuff into the blood slightly faster - but there probably isn't a lot in it.

  • Phew - now that's a real relief. I found the prospect of a three inch needle rather horrifying, TBH. (Three inch, as in I'm really fat right now. Although ~I've lost a stone and a half - only a small calf to go!)

  • Subcutaneous is by far the safest method for a beginner & far less risk of abscess than IM.

    BTW, as long as you keep needle & the site sterile, you shouldn't have any problems with abscesses.

    As for whether Sub-cut is as effective as IM, that depends on the substance. In the case of B12, if you're injecting Methyl, then yes it's designed for Sub-cut.

    If you're using Hydrox or Cyno, then it used to be said that it needed to be injected IM, as it's Methylated in muscle. I believe that has now been proven to wrong.

    Sub-cut injection is sooo easy & painless. 1/2" long insulin needle. Pinch a lump of belly fat & stick it in at 90 deg (straight in).

  • Thank you so much. Not quite as terrified and a lot more informed. X

  • Update! That shot I did 5 months ago, with too short of a needle, caused no harm.

    I now use a 1inch needle in my arm (s) and a 1.5 inch needle in the glutes. Only go in about an inch and a fourth.

    Thinking again of sub cut, mainly to see if the B12 disperses more slowly, have gone from once a week to every other day.

    My daughter, weirdly, was diagnosed with type 1 diabetes when she was 33, has to inject sub cut daily. It is autoimmune ( of course it is ,she's related to me!) and they call it diabetes type 1.5 since it had such a late onset.

    Good luck, Schenks!

  • It should disperse fine, in time. Do get it checked though as it may lead to an abcess - not a problem with treatment but you may need antibiotics.

    I hope it's OK for you. x

  • That's a good idea, to get it checked for an abcess. Wouldn't have thought of that myself.


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