B12 injections in the UK: are they worth it, and what to check first

1. Who sells B12 injections in the UK, and what do they cost?

Three routes exist, and they are not the same thing.

The NHS.If your GP finds a deficiency, the injection is hydroxocobalamin, a manufactured form of B12, given on prescription and usually at your surgery. The NHS says: “Vitamin B12 supplements are usually given by injection at first.” What follows depends on the cause, either tablets between meals or regular injections.

Boots.Boots launched a private Vitamin B12 Service on 19 November 2025 in more than 145 stores, at £29 a dose. For a single jab you need a low result from the Boots B12 blood test kit, taken within the month before. For regular doses you need a GP diagnosis of permanent B12 deficiency. The appointment takes around 20 minutes.

Superdrug.Superdrug Health Clinics charge the same £29 a dose. You bring proof of a GP diagnosis dated within three months, or take its own B12 test first. It then gives the injection every two to six months, depending on how low you are.

Private clinics. Aesthetic and wellness clinics sell them too. Some offer them as an energy boost with no blood test at all. That is the version to be wary of, and the rest of this guide explains why.

2. Do you actually need a B12 injection?

Only if you are low, and most people are not. Adults need about 1.5 micrograms of B12 a day, according to the NHS. Meat, fish, milk, cheese and eggs cover that for most people. If your body already has enough, an extra dose has nothing to fix.

Some people are genuinely short. The NHS says pernicious anaemia is the most common cause of B12 deficiency in the UK. It is an autoimmune condition, where your immune system attacks the stomach cells you need to absorb B12 from food. Diet matters too. B12 is not found naturally in plant foods, so vegans may not get enough.

Medicines can lower it as well. NICE lists metformin, proton pump inhibitors and H2 blockers, both used for acid reflux, among the risk factors. So are previous stomach surgery and coeliac disease.

The symptoms are vague. The NHS lists extreme tiredness, a lack of energy, pins and needles, a sore red tongue, mouth ulcers and muscle weakness. Low iron, an underactive thyroid and low folate produce most of the same list. That is the problem with guessing.

3. What should you check before you pay for a B12 injection?

Your B12 level, before anything goes into your arm. NICE guideline NG239, published in March 2024, is blunt about the order:

“Take blood samples for diagnostic tests before starting vitamin B12 replacement.”

NICE guideline NG239, recommendation 1.3.4

The order matters more than it sounds. Once you have had a shot, a blood test reads the shot, not you. NICE even tells clinicians to ask whether you already use over-the-counter B12, including injections and patches, before they test. Have the jab first and you lose the one number that would have answered the question.

NICE says either total B12 or active B12 will do as the first test. Total B12 is the standard measure and the one most panels carry. Active B12 measures the fraction your cells can actually use. Our vitamin B12 blood test guide explains how to read either one, and our guide to B12 levels by age shows where the cut-offs sit.

Tiredness rarely has one cause, so read B12 with the markers that mimic it:

• Folate is the B vitamin that works alongside B12. Low folate causes the same tiredness, and the NHS covers the two as one condition
• Ferritin is the protein that holds iron in reserve. Low iron brings the same tiredness and the same pins and needles, so a normal B12 with an empty ferritin is a common answer
• Magnesium is the mineral your muscles and nerves run on. Cramps and twitching are a reason to check it, rather than blame B12
• TSH and free T4 are your thyroid signal and the hormone it controls. An underactive thyroid causes tiredness and low mood that can look exactly like low B12

A full blood count adds red cell size, a classic footprint of low B12 or folate. No Helvy panel includes one, so ask your GP for that.

Two Helvy panels measure vitamin B12 from a home finger-prick sample. The General Energy & Wellness panel (£149) reads B12 with magnesium, vitamin D, thyroid (TSH and free T4), cortisol, cholesterol and CRP. It is the wide first look for someone who is tired and does not know where to start. The Vitamins & Minerals panel (£159) reads B12 with folate, a full iron workup including ferritin, vitamin D and magnesium. Pick that one if the question is whether a nutrient is behind your symptoms.

Both are analysed by UKAS-accredited UK laboratories, with results usually within 5 working days of the lab receiving your sample. Take the sample in the morning, before that day’s supplement, and before any injection.

4. Tablets or injections: which one do you need?

It depends on why you are low, and a jab bought in a shop does not answer that question.

If autoimmune gastritis, the stomach condition behind pernicious anaemia, is the cause or the suspected cause, NICE says offer lifelong intramuscular B12. No tablet gets round a stomach that cannot absorb it.

A dietary shortfall is different. NICE says the first job is to ask what you eat, check for other causes, and be aware that diet may not be the only reason. If you take an over-the-counter tablet, it needs to contain cyanocobalamin, methylcobalamin or adenosylcobalamin. NICE warns that some supplements do not contain enough, or the right type.

For a deficiency caused by a medicine such as metformin, NICE says either injections or tablets are reasonable. The choice rests on clinical judgement and your preference, and the medicine itself should be reviewed.

So a normal result means a shot is unlikely to help. A low result means you need a cause, not just a dose. That conversation belongs with a GP, and it goes better with a recent number in your hand. The same applies if you have taken tablets for months and the level has not moved.

5. What are the side effects of a B12 injection?

Mostly minor, and mostly where the needle went in. The NHS lists the common side effects of hydroxocobalamin as pain, swelling or itchy skin at the injection site, feeling or being sick, diarrhoea, headaches, feeling dizzy and hot flushes. It says serious side effects, such as a severe allergic reaction, are very rare.

Muscle cramps and body aches are not on that list. If they appear in the same week you start injections and a new supplement, nobody can say which change caused what. That is a reason to measure magnesium and vitamin D rather than guess.

On safety in general, the NHS says taking 2mg or less of B12 a day in supplements is unlikely to cause any harm. None of this makes a B12 injection frightening. It makes it a treatment for a measured shortfall, not a tonic for a bad month.

Frequently asked questions