How Soon Do You Feel the Effects of a B12 Injection?

Key Takeaways

• B12 is part of how your body turns the food you eat into usable energy, and it helps keep your nerves and red blood cells healthy.
• A shot places B12 under the skin, so it doesn't depend on your gut to absorb it.
• In one trial, adults with low-normal B12 who added B12 shots to their usual care had better mood scores after three months.
• Your provider reviews your progress before each refill, and you check in every three months.

When you start B12 shots, it's natural to wonder when you'll notice a difference. Borderline-low B12 is common, too. In national survey data from 2007 to 2018, about 1 in 8 US adults had borderline-low B12 (below 300 pg/mL).

What Can B12 + MIC Help With?

Steadier energy and a more balanced mood. B12 + MIC is a weekly shot of vitamin B12 with methionine, inositol and choline, prescribed by a licensed provider.

• Energy that keeps pace: B12 is part of how your body turns the food you eat into usable energy.
• A steadier mood: adults with low-normal B12 had better mood scores after 3 months of B12 shots.
• Healthy nerve signals: B12 helps keep your nerves and red blood cells healthy and working well.

What Does a B12 Shot Change?

Your B12 levels, without a detour through your gut. A shot delivers B12 under the skin, so your body doesn't have to absorb it through your stomach and intestine. That helps if your stomach or gut doesn't absorb B12 well.

B12 you swallow has a longer trip. Your stomach first frees it from food, then it pairs up with intrinsic factor, a protein your stomach makes, so your small intestine can take it in. Pills don't get far on that trip: only about 2% of a 500 mcg B12 pill is absorbed, and about 1.3% of a 1,000 mcg pill.

As B12 comes up, two other markers come down. B12 helps an enzyme turn homocysteine into methionine, so when B12 is low, homocysteine and methylmalonic acid build up. Bringing B12 back up lowers both.

When Might You Notice a Difference?

For mood, there's a three-month marker to go by. In one trial, adults with low-normal B12 who added B12 shots to their usual care had better mood scores after three months.

Your body keeps a store of about 1 to 5 mg of B12, which is why symptoms of low B12 can take several years to appear. Building your levels back up is a weekly routine rather than a single shot, so give it time and tell your provider how you're feeling at each check-in.

Start with an evaluation

How Liv Determines If a B12 Injection Is Needed

A licensed provider decides, after reviewing your health history and any lab results. If your provider orders labs, a B12 panel can include:

• A complete blood count (CBC): a look at your red blood cells, which need B12 to form.
• Your B12 level: the amount of vitamin B12 in your blood.
• Methylmalonic acid (MMA) and homocysteine: the two markers that change as your B12 does.

These are among the tests MedlinePlus lists for checking B12. Normal ranges vary slightly from lab to lab, so your provider explains what your own numbers mean.

Lower levels are fairly common. In national survey data, about 3.6% of US adults aged 19 and older had B12 below 200 pg/mL and about 12.5% were below 300 pg/mL.

To prepare, you may be asked not to eat or drink for about 6 to 8 hours before the test. Some medicines can affect the result, but keep taking yours unless your provider tells you otherwise.

What Can Shape Your Progress?

A few things are worth mentioning to your provider:

• Your other medicines: metformin and acid reducers can lower B12 over time. Your provider will ask what you take and factor it into your plan.
• Your schedule: you give B12 as a small shot under the skin once a week, after a starting phase your provider sets. Instructions come with your shipment.
• The rest of your week: tiredness can have more than one cause, so share the whole picture. Your provider reviews your progress and adjusts your plan as needed.

Side Effects and Safety Notes

Most people feel nothing beyond a little redness or tenderness where the shot goes in. A mild headache or looser stools can happen and usually pass.

Tell your provider if you're pregnant or breastfeeding, have a liver or kidney condition, or are allergic to vitamin B12 or cobalt, so they can confirm it's a good fit.

Ready to See Whether B12 Fits You?

When you're ready, start with an evaluation. If B12 is right for you, a licensed pharmacy prepares your shots. The wider guide to the shot covers what's in the B12 + MIC blend.

Frequently Asked Questions