NAD+ injectable claims: what the evidence actually supports

What did @the.b12.store actually say?

This creator gave a quick anatomy lesson on injection routes. They said subcutaneous injections go "under the skin and do fatty tissue for slower absorption" with common sites being the stomach, thigh, or back of the arm. Intramuscular injections go "deeper into the muscle" in spots like the deltoid, glute, or thigh, and are used for "larger, faster absorbing doses." They wrapped up by calling both routes "safe and effective, just different routes for your vitamins and nutrients."

It is a short video. No wild claims, no miracle cures, no dosing instructions. Just basic injection route anatomy aimed at people visiting their storefront. That context matters when evaluating what was said.

Does the science back this up?

Mostly, yes. The pharmacokinetic differences between subcutaneous and intramuscular delivery are well-established and the creator described them accurately in broad strokes.

Subcutaneous tissue has lower vascularity than muscle, which does produce slower, more sustained absorption for many compounds. This is why insulin, low-molecular-weight heparin, and certain peptides are routinely administered subcutaneously. A review by Usach et al. (2019, Journal of Pain Research) confirmed that subcutaneous absorption rates are generally slower and more prolonged compared to IM for equivalent compounds, though the degree of difference depends heavily on molecular weight, formulation, and injection volume.

The intramuscular route does typically produce faster absorption due to higher muscle vascularity and capillary density. Koster et al. (2015, Drug Delivery) noted IM injections allow for larger volumes and faster systemic uptake than subcutaneous routes for most water-soluble compounds. The anatomical sites the creator named, specifically the deltoid, gluteus, and thigh, are textbook IM sites supported by clinical administration guidelines from the CDC and WHO.

What did they get wrong (or right)?

They got the fundamentals right, but two things deserve a closer look. The phrase "faster absorbing doses" when describing IM injections is mostly accurate but somewhat oversimplified. Absorption speed depends on the specific compound, the formulation, and even local blood flow at injection time. Saying IM is simply faster is a reasonable generalization, not a universal rule.

The bigger issue is the phrase "safe and effective" applied as a blanket statement. That is doing a lot of work for a two-word combo. Injection safety depends on sterile technique, appropriate needle gauge, correct site rotation, and whether the compound being injected has been properly tested and sourced. Compounded vitamin injections sold at storefronts exist in a regulatory gray zone. The FDA does not approve most compounded injectables through the same pathway as licensed drugs. Calling any injectable categorically "safe" without those caveats is an oversimplification that could mislead a first-time user.

To be fair, the creator did not make any disease cure claims or prescribe specific doses. That restraint deserves credit.

What should you actually know?

If you are considering injectable vitamins or nutrients, the route of administration is genuinely relevant information and this video is a reasonable starting point for understanding the difference. That said, there are things this video did not cover that you should know before showing up at any injection clinic.

• Compounded injectables are not FDA-approved finished drug products. They are prepared under 503A or 503B pharmacy frameworks, which have quality standards but are not equivalent to approved manufacturing processes.
• Injection site rotation matters. Repeated subcutaneous injections at the same site can cause lipodystrophy, meaning localized fat tissue changes. This is documented in insulin literature (Gentile et al., 2016, Diabetes Care) and applies to any repeated sub-Q compound.
• "Vitamin shots" is a broad marketing term. B12, B-complex, glutathione, NAD, and various amino acids all have different evidence bases, different pharmacokinetics, and different risk profiles. Grouping them as interchangeable is a marketing move, not a clinical one.
• Any injection carries infection risk if sterile technique is not followed. This is not a scare tactic. It is basic microbiology.

The creator is selling a service, which is worth keeping in mind when evaluating how "safe and effective" is framed. That does not mean the information is wrong. It means you should ask follow-up questions before booking.