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"   Question Having had stomach cancer, I produce no vitamin B12. I was advised to have an injection every three months. After two months now though I suffer from severe tiredness, migraine and a tingling that starts off in the thumb and goes up my arm to my elbow.  The doctor insists that I shouldn&amp;#039;t fall into the trap of having it monthly. Please could you advise of any ill effects of having the injection more frequently?    Answer Vitamin B12 deficiency may be caused by several things. Certainly if you have had gastric surgery that will interfere with its natural absorption.  It is also interesting to note that there is a higher proportion of gastric cancer among patients with pernicious anaemia than among the normal population.  Pernicious anaemia is caused by a lack of vitamin B12. The treatment is, as you have found, replacing the inadequate absorption with regular injections of the vitamin, the common frequency is every three months.  There is no advantage in having higher than the recommended dose, although I have a very few patients who claim to feel better.  The circulating blood levels of vitamin B12 can be measured and your GP may be prepared to do this check, particularly in view of your unpleasant symptoms. Yours sincerely The NetDoctor Medical Team  Other Qs &amp;amp;amp; As Does chemotherapy affect fertility? How can I avoid radiation? Is it normal to feel pain after chemotherapy? Soya and cancer Tamoxifen and the menopause Tamoxifen, food and cancer  Last updated 02.11.2011 "^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.netdoctor.co.uk/ask-the-expert/cancer/a10390/should-i-have-a-higher-dose-of-vitamin-b12/>