Injections are still the preferred method of treating Pernicious Anaemia
Here’s what the new Guidelines for Cobalamin (B12) and Folate Disorders issued by the British Committee for Standards in Haematology say:
…the efficacy and cost–effectiveness of oral treatment in wider population-based settings has yet to be established. There are arguments against the use of oral cobalamin in initiation of cobalamin therapy in severely deficient individuals who have poor absorption, especially due to pernicious anaemia.
High dose oral cobalamin would be a reasonable alternative as maintenance in patients unable to tolerate intramuscular injections provided there is good compliance with treatment. On the other hand, some patients may prefer intramuscular injection therapy in order to assure effective treatment.
The frequency of injections varies from country to country. In the UK this is usually a 1mg injection every two to three months though many doctors prescribe more frequent injections.
The BNF states:
For people with neurological involvement
Initially administer hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement, then administer hydroxocobalamin 1 mg intramuscularly every 2 months.
For people with no neurological involvement
Initially administer hydroxocobalamin 1 mg intramuscularly three times a week for 2 weeks, then administer hydroxocobalamin 1 mg intramuscularly every 2–3 months for life.
Those injections used to be given every month in the 1960’s but this was changed to every two months in the 1970’s and to every three months in 1984.