Semaglutide/cyanocobalamin is a compounded injectable medication that combines semaglutide (the active ingredient in Ozempic and Wegovy) with vitamin B12. It is not an FDA-approved product. Instead, it’s mixed by compounding pharmacies and prescribed for weight loss or blood sugar management in type 2 diabetes, with vitamin B12 added as a secondary ingredient.
If you’ve seen this combination on a prescription label or a telehealth pharmacy website, here’s what each component does, why they’re paired together, and what you should know before using it.
What Each Ingredient Does
Semaglutide is the primary active ingredient. It belongs to a class of drugs called GLP-1 receptor agonists, which mimic a natural hormone your gut releases after eating. This hormone signals your pancreas to produce insulin, slows down how quickly food leaves your stomach, and reduces appetite by acting on hunger signals in the brain. The net effect: lower blood sugar levels and, for many people, significant weight loss.
FDA-approved versions of semaglutide (Ozempic, Wegovy, Rybelsus) are used to manage type 2 diabetes, assist with weight loss in people who are obese or overweight with related health problems, reduce cardiovascular risk, and treat a form of fatty liver disease called MASH.
Cyanocobalamin is simply a synthetic form of vitamin B12, a nutrient your body needs to make red blood cells, maintain nerve function, and produce DNA. B12 injections have been used in medicine for decades, primarily to treat B12 deficiency. On its own, B12 has no solid evidence supporting weight loss or increased energy in people who aren’t deficient, according to the Mayo Clinic.
Why They’re Combined
The most common explanation from compounding pharmacies is that vitamin B12 may help offset the gastrointestinal side effects of semaglutide, particularly nausea, which is the most frequently reported complaint among GLP-1 users. There is some early animal research suggesting a connection: a study published in Frontiers in Endocrinology found that when a GLP-1 drug was conjugated to vitamin B12 in a way that prevented it from reaching certain areas of the brain, it controlled blood sugar just as well but did not trigger vomiting in animal models. However, this is far from proof that simply adding B12 to a semaglutide injection reduces nausea in humans.
Some providers also cite general wellness benefits of B12, like supporting energy levels and metabolism. While B12 is essential for those processes, supplementing it provides measurable benefits only if you’re actually deficient. For people with normal B12 levels, extra injections are unlikely to boost energy or improve exercise performance.
In practical terms, the addition of B12 may also serve a regulatory purpose. Compounding pharmacies have historically been permitted to produce medications when FDA-approved versions are in shortage. Adding a second ingredient like cyanocobalamin can create a formulation that differs from the commercially available product, which some compounders have argued allows them to continue producing it. The FDA has pushed back on this interpretation, stating that it may still consider these products “essentially a copy” of the commercially available drug when the semaglutide and B12 strengths are within 10% of existing approved products and are given by the same route.
How It’s Typically Formulated
Compounded semaglutide/cyanocobalamin injections come in multi-dose vials rather than the pre-filled pens you’d get with brand-name Ozempic or Wegovy. Semaglutide concentrations typically range from 1 mg/mL to 5 mg/mL, while the cyanocobalamin component stays consistent at 0.5 mg/mL across all strengths. Vials are available in 1 mL and 2.5 mL sizes.
You draw the prescribed dose using an insulin syringe and inject it subcutaneously, usually in the abdomen, thigh, or upper arm, once per week. Like brand-name semaglutide, most prescribers start patients at a low dose and increase gradually over several weeks to reduce the likelihood of nausea and other GI side effects.
Storage matters. Compounded semaglutide injections need to be refrigerated. The exact shelf life varies by pharmacy, so check with the compounder that filled your prescription for specific expiration guidance.
Safety and Regulatory Concerns
The FDA has been explicit that the safety and effectiveness of combining semaglutide with other ingredients, including cyanocobalamin, has not been established. Compounded drugs in general do not go through the same testing, manufacturing oversight, or quality control as FDA-approved medications. They are not evaluated for bioequivalence, meaning there’s no guarantee that a compounded version behaves identically in your body compared to the brand-name drug.
The FDA has also flagged dosing errors with compounded semaglutide products. Because these come in vials rather than pre-filled pens with built-in dose selectors, there is more room for mistakes when drawing up the correct amount. Overdosing can cause severe nausea, vomiting, and dangerously low blood sugar, especially in people taking other diabetes medications.
Another concern involves the source of the semaglutide itself. The FDA warns that some compounders use salt forms of semaglutide, such as semaglutide sodium or semaglutide acetate, which are chemically different from the active ingredient in approved drugs. The agency has stated it has no information on whether these salt forms share the same properties as the original compound and is not aware of any lawful basis for their use.
Current Availability
Compounded semaglutide became widely available during the extended shortage of Ozempic and Wegovy that began in 2022. Under federal law, compounding pharmacies (specifically 503B outsourcing facilities) can produce copies of drugs that appear on the FDA’s official shortage list. As of now, semaglutide is no longer on that shortage list, and it does not appear on the FDA’s list of bulk drug substances with an established clinical need for compounding.
This means the legal window for compounding semaglutide has narrowed significantly. Some pharmacies continue to produce and sell it, but the FDA has signaled increasing enforcement. If you’re currently using a compounded version, it’s worth understanding that access could change and discussing alternatives with your prescriber.
Compounded vs. Brand-Name Semaglutide
The core medication is the same molecule, but the products differ in important ways. Brand-name Ozempic and Wegovy come in pre-filled, dose-locked pens manufactured under strict FDA oversight, with established dosing schedules, clinical trial data supporting their safety and efficacy, and consistent quality between batches. Compounded semaglutide/cyanocobalamin comes in vials from pharmacies that face less regulatory scrutiny, uses a combination that hasn’t been studied in clinical trials, and requires you to measure your own dose.
The main advantage of compounded versions has been cost. Brand-name semaglutide can run over $1,000 per month without insurance, while compounded versions have typically been a fraction of that price. For many people, that price difference has been the deciding factor. But lower cost comes with trade-offs in quality assurance, and the regulatory landscape is shifting in ways that may limit future availability.