B12 injections.
Methylcobalamin vs cyanocobalamin, candidacy, dosing frequency.
Most healthy adults with a varied diet absorb enough B12 from food. Injections make clinical sense in specific cases: confirmed deficiency, absorption problems from GI surgery or medications, certain dietary patterns, and patients on GLP-1 weight-loss therapy where reduced food intake can compound borderline status. We check labs before initiating long-term protocols.
Methylcobalamin vs cyanocobalamin.
B12 comes in several forms. The two clinically relevant injectable forms have different downstream behavior, and the choice isn't arbitrary.
| MethylcobalaminOur default | An active coenzyme form of B12 that the body uses directly. Better retention in tissue compared with cyanocobalamin in published studies. Slightly more expensive. Our default unless a specific reason suggests otherwise. |
|---|---|
| CyanocobalaminThe legacy form | A stable synthetic form widely available and inexpensive. The body converts it to methylcobalamin and adenosylcobalamin before using it. Effective for most patients; the conversion step is a non-issue clinically in the vast majority of cases. |
| HydroxocobalaminSpecific situations | Used in particular metabolic conditions and as a cyanide antidote at high doses. Not our routine choice for nutritional repletion. |
When injection is the right call.
Patients with documented B12 deficiency, particularly when symptoms (fatigue, neuropathy, glossitis, macrocytic anemia) and lab values agree. We confirm with serum B12 and, when borderline, methylmalonic acid.
Patients with pernicious anemia or intrinsic-factor antibodies — oral B12 simply doesn't absorb at any meaningful rate, and injection isn't a preference, it's a requirement.
Patients with prior gastric or ileal surgery (gastric bypass, ileal resection, certain bariatric procedures), where the absorption sites are anatomically altered or absent.
Patients on long-term metformin, proton-pump inhibitors, or H2 blockers, where absorption is reduced enough to produce borderline-low B12 over years.
Patients on GLP-1 weight-loss therapy with reduced caloric intake — not because the medications block B12 directly, but because lower total food volume can tip borderline status into frank deficiency.
Strict long-term vegan diets where dietary intake is genuinely inadequate. (Most vegans supplement and don't need injections.)
Loading, then maintenance.
- 01
Confirm with labs.
Serum B12 in the deficient or borderline range, with symptoms or risk factors. We don't initiate long-term injection protocols on the basis of a wellness inquiry alone.
- 02
Loading dose.
1000 mcg intramuscularly weekly for four weeks. This restores tissue stores from a depleted baseline more efficiently than a slower titration.
- 03
Maintenance dose.
1000 mcg intramuscularly monthly. Some patients with ongoing absorption issues require this indefinitely; others, after correcting the underlying cause, transition back to oral.
- 04
Re-check labs.
Serum B12 at three months to confirm response. Adjust cadence based on level and symptoms.
On wellness B12"If your B12 is mid-range and you have no symptoms or absorption issue, an injection won't make you feel different. The label says 'energy,' but the physiology says 'no.'"
- B12 injections as a generic energy boost in patients without deficiency or symptoms.
- Daily or near-daily injections — the body excretes excess B12 in urine, and frequency beyond the protocol doesn't add benefit.
- Injections during pregnancy without an obstetric coordination, even though B12 itself is safe.
- Injections in patients with cobalt allergy or known hypersensitivity to the preparation.
Supervised by Dr. Charles Peterson, board-certified physician with nearly a decade in aesthetic medicine.
Questions we get.
Will B12 give me energy?
If you're deficient, yes — correcting deficiency often resolves fatigue. If your B12 is normal, no. The placebo response to injections in this category is well-documented and not a substitute for the underlying physiology.
How often do I need a maintenance shot?
Monthly is the standard maintenance cadence for documented deficiency. Some patients with absorption issues stay on this schedule long-term; others can transition off after the underlying cause is addressed.
Can I take B12 orally instead?
For most patients with adequate absorption, yes. Oral B12 at sufficient dose is effective. We recommend injection when there's a specific reason oral won't work.
Does B12 help with weight loss?
Not directly. B12 doesn't burn fat or suppress appetite. We address B12 status in weight-loss patients because reduced food intake on GLP-1 therapy can produce or worsen deficiency — not because the injection itself drives weight reduction.
Continue.
Injectable-vs-oral rationale, candidacy, frequency, what we won't inject. No miracle claims.
GLP-1 mechanism, on-label vs off-label use, candidacy, side-effect management, what happens when you stop.