Exercise after B12 shot

[betwelve]

Some sources say not to exercise for 48 hours after a B12 injection; others say 24 and some don't mention it at all.

Also, there is a lack of consistency about the intensity; some specify "strenuous" and others do not.

I need to know as I walk and cycle everywhere so I'm not sure if I can, for example, cycle 40 minutes to the shop and 40 minutes back or not. Or can I walk (which is more tiring in a way as it takes longer)? Is this "strenuous"?

When can I go for a 10k run? etc.
My injection was yesterday at around 9 for info.

Does anyone know more about this (not from googling, I mean from medical/healthcare experience and knowledge)? I've tried phoning my doctor's but I cannot get through and I'm sure they have more urgent matters at the moment.

Thanks for any help.

I've never given it a second thought and it has never been highlighted when getting b12 injections at the doctors - I don't do anything hugely strenuous anyway but gone to classes / dog walks with zero ill effects

@betwelve

"I need to know"...

Well ask the nurse who gives the shot not a bunch of strangers on MN FFs

"FFS" - that kind of language and tone is uncalled for 🙄

I cycled to my appointment in the dark and driving rain and I was exhausted and forgot to ask, is that OK with you?

Is this the first injection? if not no need to wait.

For transparency: I've had B12 every two weeks for the last 6 years. I exercise whenever I wish, but don't take my word for it, ask the nurse, the health care professional

@user1471505356 no, not the first/loading. I have them every two months. I wouldn't want to affect the efficacy, though, as I have pernicious anaemia and was struggling as the last shot waned. I was only diagnosed this year.

As a retired haematologist, you will be find to exercise any time.

It's an injection into a muscle. Any needle / volume of fluid into a muscle can cause irritation (nothing specific to b12) so it can sometimes feel a bit sore after and if that's the case then rest the muscle / don't plan an intense workout until it feels ok.

Normal movement, walking, cycling etc should be fine but something intense like a heavy weights session that focuses on the injected muscle group is probably best left for a day or two until any soreness has settled. It won't cause lasting damage or affect the injection, it just might be sorer for longer.

I’ve had regular B12 injections for 35 years and this has literally never been mentioned as an issue. I’ve moved many times so been seen by hundreds of different nurses, doctors and haematologists, and this has never been raised.

If your muscle is sore, don’t exercise it, like for any other injection.

But otherwise crack on with whatever is normal for you.

Just to clarify, any soreness is not an issue whatsoever (within reason!); I'm just concerned with efficacy.

@user1471505356 Wow, I cannot believe I have a reply from an actual haematologist. Thank you so much. 🤩

Thanks, too, to @AltitudeCheck for their informative reply. 😊