Vitamin B12 is essential for energy production, nervous system function, red blood cell formation, and DNA synthesis. Deficiency is surprisingly common — estimates suggest that up to 15 percent of the general population may have low B12 levels, with higher rates among older adults, vegetarians, vegans, and people with certain digestive conditions. For those seeking to boost their B12 levels beyond what oral supplements can offer, two popular options exist: B12 IV therapy (delivered as part of an intravenous drip) and B12 intramuscular (IM) injections (a quick shot into the muscle). Both bypass the digestive system, but they differ in meaningful ways.
How B12 IV Therapy Works
In an IV drip, vitamin B12 — typically as methylcobalamin or hydroxocobalamin — is dissolved in a saline solution and delivered directly into the bloodstream through a vein. The infusion usually takes 30 to 60 minutes and often includes other nutrients as part of a broader IV cocktail like a Myers' Cocktail, energy drip, or immune support formula.
Because the B12 enters the bloodstream immediately, bioavailability is essentially 100 percent. Blood levels of B12 rise rapidly during the infusion. However, the body will excrete any excess B12 through the kidneys relatively quickly since B12 is water-soluble.
How B12 Injections Work
A B12 intramuscular injection is a quick procedure — a small needle delivers a concentrated dose of B12 directly into the muscle, usually the deltoid (upper arm) or gluteal muscle. The injection takes less than a minute and does not require an IV line or extended appointment.
After injection, the B12 is absorbed from the muscle into the bloodstream over a period of hours to days. This slower, more sustained absorption means that blood levels stay elevated for a longer window compared to the rapid peak-and-decline pattern of an IV drip. This is why IM injections have been the standard clinical method for treating B12 deficiency for decades.
Key Differences Compared
Absorption and Duration
IV delivery provides an immediate spike in blood B12 levels, while IM injections produce a slower, more sustained release. For most people seeking ongoing B12 maintenance, the sustained release of an IM injection may be more practical. For those who want B12 as part of a comprehensive hydration and nutrient session, the IV route offers the benefit of combining multiple treatments in one sitting.
Convenience and Time
A B12 injection takes about one minute. An IV drip takes 30 to 60 minutes. If your sole goal is B12 supplementation and you do not need hydration or other vitamins, an injection is significantly more time-efficient. Many clinics and even some pharmacies offer walk-in B12 shots with no appointment needed.
Cost
B12 injections are substantially less expensive than IV drips:
- B12 intramuscular injection — $25 to $75 per shot
- IV drip containing B12 (as part of a cocktail) — $150 to $300 depending on the formula
- B12 added to an existing IV drip — $15 to $40 as an add-on
If B12 is your primary need, injections offer better value. If you are already getting an IV for hydration or other nutrients, adding B12 is a cost-effective way to include it. For a broader look at pricing, visit our IV therapy cost guide.
Effectiveness for B12 Deficiency
For clinically diagnosed B12 deficiency, intramuscular injections are the gold standard treatment recommended by most medical guidelines. The sustained absorption pattern is well matched to the body's ability to utilize and store B12. IV delivery works as well, but is typically unnecessary when a simple injection accomplishes the same therapeutic goal.
Comfort and Side Effects
Some people dislike the brief sting of an IM injection, while others prefer it to sitting with an IV line for 30 to 60 minutes. Side effects from either method are minimal — occasional soreness at the injection or infusion site is the most common complaint. Allergic reactions to B12 are extremely rare regardless of delivery method.
Which One Is Right for You?
The best choice depends on your situation:
- Choose a B12 injection if you want a quick, affordable way to boost B12 levels without committing to a full IV session. Ideal for regular maintenance, especially if you have a known deficiency or dietary restriction.
- Choose B12 IV therapy if you want B12 as part of a broader treatment — hydration, energy, immune support, or recovery. The IV route makes sense when you are already getting a drip and want to add B12 to maximize the session.
- Choose oral B12 if your levels are only mildly low and you do not have absorption issues. Sublingual (under the tongue) B12 supplements offer reasonable absorption for maintenance in many people, though they cannot match the bioavailability of injectable routes.
For a deeper comparison of IV versus oral supplementation in general, read our article on IV therapy versus oral vitamins.
Finding B12 Therapy Near You
Both B12 injections and IV drips containing B12 are widely available. You can search for IV therapy providers in your area through our directory. Many providers offer both options, so you can discuss with their clinical team which delivery method best fits your health goals and budget.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting any IV therapy treatment.