How Long Does a B12 Shot Last? Duration, Benefits & Timing

You’ve probably heard the buzz about B12 shots for boosting energy, lifting your mood, or even supporting libido. These injections have become a popular go-to in the wellness world, but two commonly asked questions remain:  

“How long does a B12 shot last?” and “How quickly can I expect to feel results?” 

Let’s break down what you need to know—backed by science, rooted in wellness, and always with your safety in mind. 

How Long Does the B12 Shot Last? 

The effects of a vitamin B12 shot can last anywhere from a few days to a few weeks, depending on your body’s needs and current B12 levels. 

• If you’re deficient, you might feel a noticeable boost within 24 to 72 hours, with effects that last up to a week or more. 

• If you use it for general wellness, the effects might be more subtle and short-term unless combined with consistent treatments. 

Immediate vs. Gradual Effects 

Some people feel energized immediately, while others notice more gradual improvements in focus, stamina, and mood over the next few days. 

Here's what often kicks in first: 

• Within 1-3 days: Energy and alertness. 

• Within a week: Improved mood and mental clarity. 

If B12 levels were low to begin with, longer-term benefits like red blood cell production or nervous system support may take several weeks. Many of these outcomes relate to the top five benefits of getting a vitamin B12 shot, which often go beyond just boosting energy. 

What Influences How Long a B12 Shot Lasts? 

Several factors can affect how long the B12 shot lasts and how your body responds: 

• Your B12 levels: The more deficient you are, the more dramatic and long-lasting the effects may be.  

• Diet and lifestyle: Vegans, vegetarians, and those with low animal protein intake may metabolize B12 differently. 

• Absorption conditions: Certain medical conditions, like pernicious anemia, celiac disease, or gut issues, can hinder B12 absorption and make injections more necessary. 

• Age: As we age, our bodies naturally absorb B12 less efficiently. 

If you're unsure how your body might respond to a vitamin B12 shot, reviewing these FAQs can help clarify how the treatment works. 

How Often Can You Get Vitamin B12 Injections? 

Here’s where individualization really matters. Before beginning any routine, it’s best to do comprehensive bloodwork to check your current B12 levels and identify any underlying deficiencies. This ensures your treatment plan is tailored to your body’s actual needs.  

For B12 deficiency treatment, medical professionals may recommend injections: 

• Every few days for the first 1–2 weeks. 

• Followed by weekly, then monthly maintenance doses. 

For general wellness, mood, or energy support, many healthy adults opt for: 

• Weekly to monthly shots, depending on their feelings and wellness goals. 

Reminder: Always follow medical guidance when establishing injection frequency.  

How Safe Is Frequent B12 Use? 

Vitamin B12 is a water-soluble vitamin, meaning any excess is usually excreted through urine rather than stored in the body. This makes overdose extremely rare, but that doesn’t mean more is always better. 

If you have a condition like chronic fatigue syndrome, anemia, or nerve damage (often related to diabetes or alcohol use), more frequent injections may be part of your treatment plan, but only under a licensed professional’s care. 

Do B12 Shots Really Boost Energy, Mood, and Sex Drive? 

Let’s clear up the hype and dive into the science behind B12’s most talked-about benefits. 

B12 Injections for Energy and Mood 

It’s true—vitamin B12 plays a major role in energy metabolism. That’s because B12 helps your body: 

• Convert food into glucose (aka energy). 

• Support red blood cell production. 

• Maintain healthy brain and nerve function. 

However, if you’re not deficient in B12, injections may not significantly shift your energy or mood levels. Think of it as restoring your baseline, not a supercharged energy boost. 

B12 for Mood and Mental Clarity 

Low levels of vitamin B12 are often associated with: 

• Brain fog 

• Mood swings 

• Irritability or even depression 

Restoring your B12 levels, you may experience improved mental clarity and emotional stability, especially if you're already feeling off your game. 

While it’s not a substitute for therapy or mental health support, it can be a helpful tool in your overall wellness routine. 

B12 for Sex Drive 

Another trending topic: Does vitamin B12 help sexually? 

The short answer? It depends. 

Although B12 isn’t classified as a libido enhancer, its role in circulation, mood, and neurological function can still influence how you feel overall. Here’s how: 

• B12 is essential for nervous system health, which supports sexual function. 

• It may indirectly enhance blood flow, mood, and energy, which impact sexual health. 

• B12 deficiency has been associated with fatigue, low mood, and poor circulation, which can contribute to decreased sexual interest or performance. 

There’s no harm in exploring B12 as part of your sexual wellness routine—just know it’s not an aphrodisiac or instant fix. However, for those experiencing low libido due to fatigue or mood, B12 could help reset the foundation of how you feel. 

What to Expect from a B12 Shot 

To recap, here’s what you need to know: 

• How long does a B12 shot last? Typically, anywhere from a few days to a few weeks. 

• How fast does it work? Some people feel the effects within 24–72 hours, while others may see benefits over time. 

• How often can you take it? It can be taken weekly or monthly for general wellness or more frequently for medical conditions, always under medical supervision. 

To get the most out of your B12 shot, it’s a good idea to start with comprehensive bloodwork. This helps identify any vitamin deficiencies or imbalances so your provider can tailor a plan that fits your specific needs. 

At Liquivida, we offer personalized wellness consultations to help you understand what your body truly needs, so you’re not just treating symptoms, but supporting long-term health. 

Whether you're looking to boost your energy, support your mood, or give your wellness routine a glow-up, vitamin B12 shots can be a safe, effective tool, especially when guided by lab results and a licensed provider. 

Important: Always talk to your doctor or a certified wellness expert (like the team at Liquivida!) before starting B12 injections to ensure they’re right for you.