Does Ozempic contain B12? No, Ozempic (semaglutide) does not contain vitamin B12. This GLP-1 receptor agonist is formulated solely with semaglutide as its active ingredient, alongside pharmaceutical excipients for stability. Confusion sometimes arises because other diabetes medications, particularly metformin, are known to interfere with B12 absorption. Whilst Ozempic itself does not affect B12 metabolism directly, patients using this medication—especially those taking metformin concurrently—should remain vigilant about their nutritional status. Understanding what Ozempic does and does not contain helps inform appropriate monitoring and supplementation strategies for people with type 2 diabetes.

Does Ozempic Contain Vitamin B12?

No, Ozempic does not contain vitamin B12. The medication is formulated solely with semaglutide as its active pharmaceutical ingredient, alongside pharmaceutical excipients necessary for stability and administration. There is no vitamin B12 (cobalamin) included in the formulation, nor is it added as a supplementary component.

This is an important clarification because confusion sometimes arises from the fact that certain other diabetes medications—particularly metformin—are well-documented to interfere with vitamin B12 absorption. Patients taking multiple medications for type 2 diabetes may conflate the effects of different drugs, leading to questions about whether Ozempic itself contains or affects B12 levels.

Ozempic (semaglutide) is a glucagon-like peptide-1 (GLP-1) receptor agonist administered via subcutaneous injection once weekly. Its mechanism of action involves enhancing insulin secretion in response to elevated blood glucose, suppressing glucagon release, slowing gastric emptying, and reducing appetite. None of these pharmacological actions directly involve vitamin B12 metabolism or supplementation.

Whilst Ozempic does not contain B12, patients using this medication—particularly those with type 2 diabetes who may be taking other medications concurrently—should remain vigilant about their overall nutritional status. The gastrointestinal effects of Ozempic, including nausea, vomiting, and altered eating patterns, can indirectly influence nutritional intake. According to the MHRA-approved Summary of Product Characteristics, there is no established link between semaglutide use and vitamin B12 deficiency through direct pharmacological interaction. Understanding what Ozempic does and does not contain helps patients and healthcare professionals make informed decisions about nutritional monitoring and supplementation strategies.

What Are the Active Ingredients in Ozempic?

Ozempic contains semaglutide as its sole active pharmaceutical ingredient. Each pre-filled pen delivers semaglutide in concentrations designed for once-weekly subcutaneous administration, with available dosing strengths of 0.25 mg, 0.5 mg, 1 mg, and 2 mg per injection. Semaglutide is a synthetic analogue of human GLP-1, modified to extend its half-life to approximately one week, enabling weekly dosing.

According to the MHRA-approved Summary of Product Characteristics, the formulation also contains several inactive excipients that serve specific pharmaceutical purposes:

• Disodium phosphate dihydrate – provides buffering capacity to maintain pH stability

• Propylene glycol – acts as a co-solvent and stabilising agent

• Phenol – functions as an antimicrobial preservative

• Water for injections – serves as the vehicle for the solution

• Hydrochloric acid and/or sodium hydroxide – may be used for pH adjustment

These excipients are standard pharmaceutical ingredients used in injectable medications and are present in carefully controlled quantities to ensure product stability, sterility, and patient safety. None of these components provide nutritional value or vitamin supplementation.

The mechanism of action of semaglutide involves binding to GLP-1 receptors on pancreatic beta cells, enhancing glucose-dependent insulin secretion. It also acts on receptors in the brain to reduce appetite and on the gastrointestinal tract to slow gastric emptying. This multi-targeted approach contributes to improved glycaemic control and weight reduction in people with type 2 diabetes.

Ozempic is indicated as an adjunct to diet and exercise to improve glycaemic control in adults with type 2 diabetes mellitus. It may be used as monotherapy when metformin is inappropriate, or in combination with other glucose-lowering medications. Understanding the precise composition of Ozempic helps clarify that any nutritional concerns, including B12 status, require separate assessment and management rather than being addressed by the medication itself.

Why B12 Deficiency Matters for People Taking Ozempic

Whilst Ozempic does not directly cause vitamin B12 deficiency, people with type 2 diabetes taking this medication may be at increased risk of B12 insufficiency for several important reasons that warrant clinical attention.

Metformin co-prescription represents the most significant risk factor. Many patients prescribed Ozempic are already taking metformin, which is commonly used as first-line therapy for type 2 diabetes according to NICE guidelines (although SGLT2 inhibitors may be first-line in certain cardio-renal risk groups). The MHRA Drug Safety Update highlights that metformin interferes with calcium-dependent B12 absorption in the terminal ileum, and long-term use is associated with reduced serum B12 levels in a significant proportion of patients. The combination of metformin with Ozempic does not create a synergistic effect on B12, but the metformin component alone necessitates monitoring.

Gastrointestinal side effects of Ozempic—including nausea, vomiting, diarrhoea, and reduced appetite—are common, particularly during dose titration. These effects can lead to:

• Reduced dietary intake of B12-rich foods (meat, fish, dairy, eggs)

• Altered eating patterns with potential nutritional inadequacy

• Reduced nutritional intake if gastrointestinal symptoms are severe or prolonged

Vitamin B12 deficiency can manifest with significant clinical consequences, including macrocytic anaemia, peripheral neuropathy, cognitive impairment, fatigue, and mood disturbances. In people with diabetes, these symptoms may overlap with or be mistaken for diabetic complications, potentially delaying diagnosis.

Pre-existing risk factors common in the diabetes population further compound concern:

• Older age (reduced intrinsic factor production)

• Autoimmune conditions (pernicious anaemia, thyroid disease)

• Previous gastric surgery or gastrointestinal disorders

• Vegetarian or vegan dietary patterns

• Proton pump inhibitor use (reduces B12 absorption)

There is no established link between semaglutide pharmacology and B12 metabolism in the MHRA-approved product information, but the clinical context in which Ozempic is prescribed creates a population where B12 awareness is prudent. Healthcare professionals should maintain vigilance regarding these intersecting risk factors when managing patients on GLP-1 receptor agonists.

How to Monitor and Maintain B12 Levels on Ozempic

Proactive monitoring and management of vitamin B12 status may be appropriate for patients taking Ozempic, particularly those with additional risk factors. A structured approach should align with UK clinical guidance.

Assessment considerations include:

• Serum B12 measurement may be considered before initiating Ozempic in high-risk patients (those on metformin, older adults, those with gastrointestinal symptoms, or with restricted diets)

• Testing for B12 deficiency should be performed in patients on metformin who develop symptoms suggestive of deficiency, as advised by the MHRA Drug Safety Update

• Consider periodic monitoring in patients with risk factors for B12 deficiency, rather than routine annual testing for all patients

• Full blood count to identify macrocytic anaemia, which may indicate B12 or folate deficiency

• Clinical assessment for symptoms of deficiency: fatigue, paraesthesia, cognitive changes, glossitis, or balance problems

If B12 levels are borderline or if clinical suspicion remains despite normal serum B12 (measured in pmol/L, with laboratory-specific reference ranges), additional testing may be considered according to local laboratory protocols. This might include methylmalonic acid, homocysteine, or holotranscobalamin (active B12).

Dietary optimisation represents the first-line approach for maintaining adequate B12 status:

• Encourage consumption of B12-rich foods: meat, poultry, fish, eggs, dairy products

• For vegetarians and vegans, recommend fortified foods (cereals, plant-based milk alternatives) or supplementation

• Address any gastrointestinal symptoms that may be limiting dietary intake

Supplementation strategies depend on the severity of deficiency and absorption capacity, following British Society of Haematology and BNF guidance:

• Oral B12 supplementation may be appropriate for mild deficiency or prevention in at-risk individuals with intact absorption, with dosing according to local protocols

• Intramuscular hydroxocobalamin injections are indicated for confirmed deficiency:

• With neurological involvement: 1 mg on alternate days until no further improvement, then 1 mg every 2 months
• Without neurological involvement: 1 mg three times a week for 2 weeks, then 1 mg every 3 months

Patient safety advice includes:

• Contact your GP if you develop persistent tingling, numbness, unusual fatigue, memory problems, or mood changes

• Inform healthcare providers of all medications, including over-the-counter supplements

• Attend scheduled blood test appointments for diabetes and nutritional monitoring

• Do not stop prescribed medications without medical advice

• Report any suspected side effects to the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk or via the Yellow Card app)

Healthcare professionals should adopt an individualised approach, considering the patient's complete medication profile, dietary habits, symptom burden, and laboratory findings. Regular review ensures that nutritional status is maintained alongside optimal glycaemic control, supporting overall health outcomes for people with type 2 diabetes taking Ozempic.

Frequently Asked Questions