Suspected fibrous myopathy in legs after frequent B12 thigh injections

[PointOfReference]

Has anyone had stiff legs/myopathy after frequent, daily injections into their thighs?

Ive tried to rule everything else out but it seems like both thighs are stiff and calves are weak. Theres also muscle atrophy.

Is this common?

[Foggyme Administrator]

It’s not common with IM injections of vitamin B12. Fibrous myopathy is usually caused by the toxicity of the drug injected, rather than injection itself.

B12 is water soluble and easily absorbed by the muscles - it lacks the toxicity that is the usual cause of muscle damage.

Here's a link to a research paper that investigated the potential toxic effects of various drugs that are commonly injected - B12 was found to cause no damage.

europepmc.org/backend/ptpmc...

It would be a good idea to discuss this with your GP - myopathy and muscle weakness and atrophy can have other causes which may need to be ruled out.

[PointOfReference in reply to Foggyme]

Very helpful, many thanks

In discussions with GP so hopefully further testing will help

[Foggyme Administrator in reply to PointOfReference]

Good luck - be interested to hear how you get on.

[Cherylclaire Forum Support]

Have had weak leg muscles and stiff gait from B12 deficiency. Walking uphill particularly difficult work, and having to think too hard to get legs to keep moving: felt like I'd forgotten how to flex calf muscles and like a physio band around legs above the knees. I don't have the same problem now with walking - what once took an exhausting teeth-gritting hour is now back to an easy 20 minutes - without a 2 or 3 hr nap at the end.

Standing still for a while, as when preparing dinner, would cause legs to shake. Had a similar problem with arms- decorating Christmas tree would require a day of doing a bit until hands shook, resting, doing a bit more etc, remember it taking a couple of days.

This doesn't happen now, either.

I have been left with two symmetrical patches of numbness though: outer side of shins.

No problems found with electric tests- so not main nerves.

This is not necessarily what you are experiencing - just one possible explanation.

I'd do as Foggyme has already advised - there are other causes to explain what you are experiencing and you will need the help of a GP to eliminate these.