Vitamin B12 dosage and reconstitution
A vitamin shot that fixes tiredness only when low B12 is the cause. Cheap, very safe, and a blood test tells you if it is for you.
UnderstandWhat it isApplyHow to use it
Staying safe
Things people sometimes notice
- A sore spot or small bruise where you injected
- Bright yellow urine for a day, which is the extra B12 leaving
- Mild warmth or flushing for a few minutes
Stop and get help if (trouble breathing or swelling: call 911)
- Hives, swelling of the face or throat, or trouble breathing, a rare allergy to cobalt or the preservative
- Sudden leg swelling or breathlessness in the first days of a loading course
Talk to your doctor first, especially if
- You have Leber's disease, a rare inherited optic nerve condition; cyanocobalamin injections can worsen it
- You have had a low potassium reading, since fast correction of a severe anemia can drop potassium further
- You take metformin or a daily acid blocker; these lower B12 over time and a yearly level is worth building in
- You are being treated for a severe anemia, where the first week of loading is usually watched with blood counts
Mixing it
B12 usually comes ready to use as a liquid (often bright red), so there is typically nothing to mix. Confirm your dose with the calculator and inject subcutaneously (subQ) or into muscle.
Confirm the strength and your dose.
Clean the injection site with alcohol.
Inject subcutaneously (subQ) or into muscle.
Weekly is a common maintenance rhythm.
Store per the product label, away from light.
The short version
What it isA vitamin shot that fixes tiredness only when low B12 is the cause. Cheap, very safe, and a blood test tells you if it is for you.
EvidenceAnimal 5/5 · Human 5/5 · Approved
Want the background?What it is and the research
This is education, not medical advice. Doses shown are the patterns people commonly follow, not a prescription. Talk with a doctor before starting, especially if you take other medicines or have a health condition.