What Is L-Carnitine? Dosage, Half-Life & How to Track It
Also known as: Levocarnitine · Carnitor (brand) · LC
L-Carnitine is an amino-acid derivative your body already makes and uses to shuttle fatty acids into mitochondria for energy production. Subcutaneous dosing — typically 50–100 mg once daily, up to 200 mg on advanced protocols — delivers close to 100% bioavailability, versus just 5–18% for large oral doses, and skips the gut conversion linked to TMAO, a compound tied to cardiovascular concerns. Educational information only.
What L-Carnitine is and how it works
L-Carnitine isn’t a novel research peptide — it’s an amino-acid derivative your liver and kidneys already synthesize, and its job is fatty-acid transport: it shuttles fat molecules across the mitochondrial membrane so they can be broken down (β-oxidation) for energy. Without enough carnitine, that transport step bottlenecks, and less fat gets used for fuel regardless of what else you’re doing.
The reason it shows up in this list rather than the supplement aisle is the delivery route. Oral L-carnitine has notoriously poor and inconsistent absorption at meaningful doses (roughly 5–18% bioavailability), and a portion of what you do absorb gets converted by gut bacteria into TMAO, a metabolite that’s been associated with cardiovascular risk in some research. Subcutaneous injection routes around both problems — it delivers close to 100% of the dose and bypasses the gut entirely.
It’s worth being clear-eyed about the framing: this is a legitimate, well-understood physiological mechanism, not a novel or experimental compound — the “protocol” below is really just an efficient delivery method for something your body already does.
Typical dosing & reconstitution
Dosing is simple compared to the multi-step titration ladders elsewhere in this group:
- Weeks 1–2: 50 mg once daily
- Weeks 3–12: 100 mg once daily (maintenance)
- Advanced protocols: up to 200 mg/day, often split into two injections
| Vial | BAC water | Concentration | 1 unit (U-100) ≈ |
|---|---|---|---|
| 200 mg | 2 mL | 100 mg/mL | 1 mg |
At 100 mg/mL, the numbers line up cleanly: a 100 mg maintenance dose is exactly 100 units — a full 1 mL syringe. Doses above that (advanced 150–200 mg protocols) are typically split into two injection sites for comfort rather than drawn as one large shot.
Half-life & what it means for frequency
L-Carnitine’s half-life is dose-dependent, generally cited in the range of roughly 6 to 15 hours, which comfortably supports once-daily dosing without much level-to-level carryover to think about.
Because it’s a compound your body already produces and regulates, there isn’t the same accumulation-to-steady-state story as an exogenous GLP-1 agonist — daily dosing is simply about maintaining a consistent supply for the fat-transport pathway to use, not building toward a plateau.
What to track & common side effects
L-Carnitine is generally well tolerated; the main practical issue reported at high oral (not injected) doses is a fishy body odor from a gut-bacteria metabolite (TMA) — subcutaneous dosing largely sidesteps this since it skips gut metabolism.
What’s worth tracking is mundane by design: the daily dose and streak, since consistency is the entire mechanism here — there’s no titration curve or dramatic side-effect pattern to watch for, just whether you’re actually taking it every day.
How to track L-Carnitine in Stackeddd
Log the daily dose and keep the streak — L-Carnitine’s whole value case is consistent daily supply, so a tracked streak is more useful here than for almost anything else in this list. Get the reconstitution dialed in once and the units are locked in for the rest of the protocol.
Model it yourself · free, no account
Reconstitution Calculator
Model it yourself: enter your vial size and BAC water and the Peptides tab returns concentration and exact units for any dose — the same math built into the Stackeddd app.
Related compounds
Related reading: Peptide reconstitution math: how much BAC water to add
Frequently asked questions
What is L-Carnitine used for?
It’s a naturally occurring amino-acid derivative that transports fatty acids into mitochondria for energy production. Subcutaneous dosing is used to bypass the poor oral bioavailability (5–18%) and TMAO-linked gut conversion of oral supplementation.
What is the half-life of L-Carnitine?
Roughly 6 to 15 hours depending on dose, which comfortably supports once-daily dosing without significant carryover between doses.
Why inject L-Carnitine instead of taking it orally?
Subcutaneous injection delivers close to 100% bioavailability versus 5–18% for large oral doses, and it skips the gut-bacteria conversion to TMAO, a metabolite linked to cardiovascular concerns in some research.
How much L-Carnitine should you take daily?
A common protocol starts at 50 mg/day for the first two weeks, then moves to a 100 mg/day maintenance dose; advanced protocols go up to 200 mg/day, usually split into two injections.
This is educational information, not medical advice. Doses and protocols above reflect published references and community practice — protocol decisions belong with your prescribing physician. Generic names used throughout. How this reference is built & how the AI is tested →
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