Missed B12 injection should I double up? - Pernicious Anaemi...

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Missed B12 injection should I double up?


I have PA and I normally have B12 injections every 10 weeks. I recently discovered I've accidentally missed a dose (there's a lot going on in my life at the moment).

I've got an appointment for an injection on Monday - it's almost 20 weeks since my last injection and it's therefore almost 10 weeks overdue. I'm getting symptoms again after years of good management – the tiredness started a couple of weeks ago and now my memory and concentration seem to be affected again.

Should I see my doctor and request a second injection to make up for the one I've missed? Or is resuming the 10 week routine enough?

18 Replies

I would check with your doctor as symptoms have returned. I'm still unsure if anyone can store b12 from injections. If you can I expect you will need topping up

I'm sure more experienced people on here can advise too. Hope your symptoms go soon. Horrid reminder!

smish in reply to Nackapan

Thanks, Nackapan. I'll make an appointment with the GP, too. Bad that I feel nervous opening up the topic with a doctor in case they make me take a test or make me go back to three monthly jabs.

smish in reply to smish

I read the PAS description of the PA fog earlier "handbag in fridge syndrome" - made me laugh. When I was really bad years ago I poured boiling water into the tea caddy instead of the tea cup - mmm nice strong cuppa. Another time I put the milk in the cupboard and a cup in the fridge... It's funny really.

Nackapan in reply to smish

That is funny. Yesterday I added milk to hot blackcurrant. ..yum ...not

Ritchie1268 in reply to Nackapan

I went to bathroom other day for a shower. Put my clothes on the floor ready to put in washing machine after my shower.

Had a tiddle, took my socks off & chucked in the toilet, before I flushed it!!! 🙄🤔

smish in reply to Ritchie1268


smish in reply to smish

More "handbag in fridge" stories, please. Laughing is making the whole thing a lot more bearable!

Ritchie1268 in reply to smish

You're absolutely right. If you didn't laugh you'd drive yourself mad! 😆

H212312 in reply to smish

I lost the butter once, looked in the fridge multiple times in case I was overlooking it. Found it the next day in the saucepan cupboard 🤦‍♀️

smish in reply to H212312

Hahaha! If I'm honest, I really freak out when this happens to me, but having shared stories with you all – and having an injection in the diary and the reassurance that should sort things out again – I'm really seeing the funny side. When your care isn't properly in place, it is a frightening place to be. I had a very slow diagnosis (it was 20 years ago) and when the confusion kicked in I kept making glaring errors at work (I'm a perfectionist so that was horrifying to me), cried all the time, fainted on the train home from work, got my first migraines. It was a mess. I'm very thankful things have been managed so well for the last 8 years or so. I'm pretty much symptom free (except for this daft blip).


Hi smish. I'd suggest having your injection and then assessing after that. Having a second injection immediately (if that's your intention) may not help since excessive B12 is simply excreted in the urine.

Your injection may last you until your next injection is due according to your usual regime. If it does, then no problem. However, if you find symptoms returning before your next next 10 week injection, you could approach your GP and ask to have your injections every eight weeks (the BNF guidelines have recently been changed and now state that B12 injections can be given every 2-3 months - your GP can look online to see these changes).

However, in the long-term, if ten weekly has previously been working for you it's more likely that this is a 'blip' because you missed one out - and continuing on your usual regime will work on an ongoing basis.

Think you’re right to be cautious about approaching your GP right now...some do have a tendency to test levels and reduce frequency or even stop injections. Wrong, as you know. Depends on how knowledgable your GP is...and only you can know that 😉.

In an ideal B12 world it would be nice to think that if you have your jab and then symptoms return before your next jab is due according to schedule, you could pop along, explain your oversight / missed injection, and ask for a 'top-up'...but we all know how that often works...

So...in short...suggest you have your injection and then see what happens.


smish in reply to Foggyme

Thanks, Foggyme. Really appreciate that. I think your suggestion of having the injection on Monday and then resuming the 10 week plan and seeing how I go is less risky than an appointment with the doctor.

FoggymeAdministrator in reply to smish

Great idea smish...but oh how sad and bad that appointments with doctors are such risky issues for we B12 deficients!

Hope you manage to get through the ten weeks...👍

smish in reply to Foggyme

Thanks! So helpful to get your perspective on all this.

clivealiveForum Support

HI smish I have to agree with Foggyme that it would be a waste to double up on your next scheduled B12 injection and hopefully your returning symptoms will be put in abeyance once your routine is back to normal.

I've only once in over 46 years "forgotten" to have an injection appointment and fortunately my surgery nurse "fitted me in" the following day. I seem to remember I was more worried and upset at missing the appointment than the injection as my surgery were pretty severe on "no shows" and I was quite young back then.

I am not medically trained and wish you well.

smish in reply to clivealive

Oh gawd, me, too. I feel really dumb! Trouble is I was having brain fog while trying to persuade the reception team to get me in with a nurse or GP for the jab sooner than Tuesday so kept saying all the opposite numbers so probably sounded like I was a clown.

You won’t need a second dose - you will be surprised how this top up will help - ask for blood test if worried - but over 35 yrs I’ve missed many x

smish in reply to Frenchiebabe

Thanks. Good to know I'm not the only one who messes up occasionally!

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