The short version.
Two practical routes dominate clinical NAD+ use: intravenous (IV) infusion and subcutaneous (subq) injection. Each has a different pharmacokinetic profile, different tolerability concerns, and different real-world friction. There's no "objectively better" — the right choice depends on use case, schedule, and how your body handles the rate of administration.
IV produces a fast, large rise in plasma NAD+ over the duration of an infusion (typically 1-3 hours). Subq is slower, smaller in peak, and produces a more distributed exposure. The infusion experience is also notoriously different — IV NAD+ at high rates is famously uncomfortable; subq is more like a routine peptide injection.
| Topic | IV NAD+ | Subq NAD+ |
|---|---|---|
| Onset | Direct circulation; high peak during infusion | Slower absorption; lower peak |
| Session length | Typically 1-3 hours, in clinic | Minutes, self-administered at home |
| Tolerability | Flushing, nausea, chest pressure if rate is too fast | Generally well-tolerated; injection-site reactions possible |
| Practical friction | Clinic visit; clinical supervision | Home injection; standard subq workflow |
| Best fit | Periodic high-dose protocols, supervised setting | Routine, lower-dose, ongoing use |
Pharmacokinetics, tolerability, friction.
IV. The defining feature of IV NAD+ is the rate-of-infusion problem. Push it too fast and you get the classic constellation: chest tightness, flushing, abdominal cramping, anxiety. Slow the rate and the same total dose is well-tolerated. That's why a higher-dose IV is delivered over hours, not minutes. The clinical experience is supervised, longer, and produces the highest plasma peaks. For people doing periodic high-dose protocols, it's the standard route.
Subq. Subcutaneous injection avoids the rate problem because absorption is naturally slow. You miss the IV peak, but you also miss the discomfort. Subq fits a maintenance use case: smaller, more frequent, self-administered, lower disruption. See the standard subq injection workflow →
Most people who run NAD+ ongoing land on subq for the schedule and the practical home workflow. People who want an occasional "loading" dose or are using NAD+ for a specific event (recovery, travel, post-surgery) often prefer IV under supervision. Plenty of patients use both — IV every few weeks plus subq in between.
IV is fast, supervised, sometimes uncomfortable. Subq is slow, routine, low-friction. Most people end up choosing for lifestyle reasons.
Why oversight matters.
The internet sells almost any peptide as research chemicals — vials with disclaimers, no prescription, no provider, no follow-up. The risk isn't theoretical. Sterility, peptide identity, peptide content, and contamination all vary widely between gray-market vendors. The FDA has been explicit that compounded drugs aren't FDA-approved, and that research-only labels don't protect consumers when products end up in human use.
Oversight isn't a bureaucratic checkbox. It's a U.S.-licensed prescriber who reviews your history before prescribing, a 503A compounding pharmacy that sources active pharmaceutical ingredient and prepares the medication under USP 797 sterile standards, and a follow-up cadence that lets someone catch a problem before it becomes a worse one.
How Boswell handles this.
Boswell pairs you with a U.S.-licensed physician for the intake. They review your goals, medications, history, and any contraindications before prescribing. If a protocol isn't appropriate, you don't get it. If it is, the prescription goes to a 503A compounding pharmacy that prepares the medication under sterile compounding standards, labels it for you specifically, and ships it directly.
Refills aren't automatic — they involve a check-in. The point isn't to gate access; it's to keep someone clinical in the loop while you're on therapy. How Boswell works →
Questions worth asking your provider.
- Given my goals, does periodic IV plus maintenance subq make more sense than one or the other?
- If I'm sensitive to flushing or have cardiovascular history, should I avoid IV?
- What's the simplest schedule that gets me to the outcome we're targeting?
- How will we tell whether I'm responding?
- What rotation or site-management practices matter for subq long-term?
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