Pernicious Anaemia Society
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Dental injections

Being a dedicated reader of all posts and being B12 def, I saw a comment about dental injections recently. I am now facing complicated dental procedures and wonder if there is anything I should be aware of? Is it just a coincidence that 7 years ago my illness and resultant discovery of B12 deficiency was following complicated dental procedures? Any advice would be much appreciated.

8 Replies

The problem is, I believe, the anaesthetic - important to avoid nitrous oxide - which goes for any type of surgery, whether dental or otherwise, as nitrous oxide will oxidise the effective part of the B12 molecule with the result that your body won't be able to use it.

This is why many people who have an undiagnosed malabsorption problem, suddenly find a whole load of symptoms getting worse or even appearing for the first time after surgery. My own experience was an operation to pin an ankle - whilst I now realise that oxidisation had made problems worse I just remember things being extremely difficult after the operation ... not that they had been that great before - and waking up with no real feeling in the pinned ankle - yes could have been partly down the op but as it didn't return until I started supplement B12 for myself I don't think that was the whole story.

Please make sure that your dentist is aware that you have a condition that means you can't process B12 normally from your diet and you are aware that nitrous oxide can make any B12 in your body inactive, so you would like them to avoid nitrous oxide as an anaesthetic and like them to reassure you that they have double checked that there aren't any similar issues with any other anaesthetic that they are planning to use.

If nitrous oxide is unavoidable (not that it should be) then you should be in contact with your GP to make sure that you receive loading shots etc immediately after to replace the oxidised B12 - though they will probably look at you like a mad thing and dismiss you as a lunatic ... such is the scale of ignorance.

Some dentists are quite good with B12 - it was often in the past dentists who picked up the problem because one symptom is swollen and discoloured tongue. However, I'm not sure that it features so much on syllabus these days ... and I suspect that the possiblity that dental problems - frequent infections etc - could be down to B12 is something that a lot of them are not that aware of.

Feel myself getting a bit ratty - and know I didn't take any hydroxo this morning so time to get a fix otherwise I'm going to start biting people's heads off.

Hope this helps a bit.


Thank you Gambit you really are a star. I will talk again with my dentist before letting him loose on my teeth!


Yes, but...nitrous oxide, I don't think, is not given by injection. Expect fuel injection.

I too, saw the post about the injection and resulting problems and wondered what the injection was.

Bearing in mind that a good few years ago now, if the dentist injected the top of my mouth my nose would bleed.

So I don't think we are talking nitrous oxide but I'm not 100% certain. Anyone else got any ideas?


Its the laughing gas they sometimes give you see:

"Nitrous Oxide, also called 'Laughing Gas' or Dental Anesthesia is a gas that is often given for dental procedures and other 'minor' medical procedures to provide mild relaxation for the procedure. "

Read more:

Its only N20 that can cause a problem, it does not mean that all anaesthetics are harmful if you have a problem absorbing B12, see:

"Nitrous oxide (N2O) exposure.

N2O inactivates cobalamin. When unrecognized and untreated clinical cobalamin deficiency (eg, PA) exists preoperatively, summation can produce rapid neuropsychiatric deterioration, especially after prolonged exposure.69 Routine cobalamin and MCV testing is advisable before surgical or dental procedures involving N2O exposure, especially in the elderly. Patients with abnormal results must be evaluated fully, and, if necessary, fully treated. Patients with conditions that predispose to deficiency, such as prior gastric surgery, should be treated by injection before surgery and by either route thereafter."

Make sure your dentist knows you are on B12 treatment,

Kind regards,




I mentioned N20 to my dentist and B12 injections when I was due to have a replacement filling. He said he had never heard of it.

1 like

Is that the same one they call 'gas and air' in labour?





For me, the Injections of anisthetic were painful. because it was a tooth extraction, the dentist gave me pain killers- ibuprofen- the roof of my mouth and half my face was tender for about a week. Things significantly improved after the B12 injection


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