Injections of cyanocobalamin, or vitamin B12, normally get administered daily to start. They are then given every other day for two to three weeks, and then monthly to treat pernicious anemia, according to Drugs.com. Adults with pernicious anemia usually take vitamin B12 injections for life. Dosages for malabsorption differ from these time frames.
The initial dose includes 1,000 micrograms, given intramuscularly and every day, for the first seven days of vitamin B12 injections, notes Drugs.com. If conditions improve with the initial dose, doctors may continue the same dosage amount every other day for seven more days, and then once every three to four days for another two to three weeks. Patients typically receive monthly injections between 100 and 1,000 micrograms for their entire lives to treat pernicious anemia.
If infants require vitamin B12 injections, they receive 0.2 micrograms per kilogram of body weight per day for two days, says Drugs.com. For the next five days, infants may receive 1,000 micrograms per day, followed by 100 micrograms per month. Children usually get 30 to 50 micrograms daily for two or more weeks, and then 100 micrograms per month.
For adults without pernicious anemia, but vitamin B12 malabsorption problems, the pediatric dosing schedule is recommended, explains Drugs.com. Patients diagnosed with vitamin B12 malabsorption get a total dose of 1.0 to 1.5 milligrams over two weeks to a month, and then doctors usually put them on monthly maintenance shots of 100 micrograms.