B12 deficiency may be treated with tablets or injections, depending on the circumstances. Severity, nervous-system involvement and the response to treatment help determine the choice. Injections are not automatically better for everyone who feels tired.
The cause matters too
Deficiency can involve low intake or impaired absorption. Your clinician needs to know your diet, medicines and any stomach or bowel disease or surgery. A plan to correct deficiency should also explain how recurrence will be prevented.
Say if you already take a B12 supplement when tests are arranged. A sample after starting self-treatment may need a different interpretation from an untreated baseline.
Two treatment routes
| Treatment | Question for the clinician |
|---|---|
| B12 tablets used as medicine | Is this dose and approach appropriate for my type of deficiency? |
| B12 injections | Is there severe deficiency, nerve involvement or another reason for injections? |
| Maintenance treatment | Will I need ongoing treatment after the initial phase? |
Take nerve symptoms seriously
Numbness, tingling and balance problems may need prompt assessment. Do not wait months for a non-prescription supplement to solve new or worsening symptoms. They can have causes other than B12 deficiency, so appropriate assessment matters.
Call 112 for sudden one-sided weakness, facial weakness or speech difficulty. These symptoms should not be assumed to be a vitamin problem.
Follow-up is more than another B12 number
Ask which symptoms and blood results will be monitored and when. If haemoglobin or symptoms do not improve as expected, the diagnosis or treatment may need reconsideration. Do not increase doses without a plan.
- What is thought to be causing my deficiency?
- How long will the initial treatment last?
- What improvement is expected and when?
- Who should I contact about new nerve symptoms?
Can folic acid replace B12?
No. B12 deficiency needs consideration before folic acid treatment starts, because the blood picture can improve while nerve problems persist or worsen. Discuss combined supplements with your vårdcentral, a primary care centre, or pharmacy. In Sweden call 1177 if you need advice about the urgency of symptoms.
Sources and further reading
- 1177: Brist på vitamin B12 (in Swedish)
- Läkemedelsboken: Behandling av brist på B12 och folat (in Swedish)
- 1177: Stroke (in Swedish)
Sources and links checked on 22 October 2026. Editorial team: Hagakliniken. General information; individual assessment may differ.