L-Carnitine
Also known as: Levocarnitine, L-Carnitine Injectable, Carnitine
Amino Acid Derivative | Fatty Acid Transporter
Overview
L-Carnitine is an amino acid derivative naturally produced in the body and essential for transporting long-chain fatty acids into mitochondria for energy production. Injectable forms bypass digestive absorption limitations of oral supplements.
Key benefits
- Enhanced fatty acid transport to mitochondria
- Improved energy production from fats
- Better bioavailability than oral forms
- Support for exercise recovery
- Potential cognitive benefits
Mechanism of action
Acts as a carrier molecule, shuttling long-chain fatty acids across the inner mitochondrial membrane via the carnitine palmitoyltransferase (CPT) system. This is the rate-limiting step in fatty acid oxidation for energy production.
Molecular data
- Type
- Quaternary ammonium compound
- Half-life
- ~2-3 hours (injectable)
Indications
What the research community uses this compound for, with self-reported effectiveness.
Metabolic
Fatty Acid Oxidation
Most effectivePrimary function transporting fatty acids into mitochondria for beta-oxidation.
Energy Production
EffectiveSupports ATP generation from fat metabolism, particularly during exercise.
Weight Management
ModerateMay enhance fat utilization when combined with exercise and caloric deficit.
Performance
Exercise Recovery
ModerateMay reduce muscle damage markers and improve recovery post-exercise.
Endurance Support
ModerateEnhances fat utilization during prolonged exercise, potentially sparing glycogen.
Clinical Uses
Carnitine Deficiency
Most effectiveFDA-approved treatment for primary and secondary carnitine deficiency.
Dialysis Support
EffectiveUsed in patients on hemodialysis who develop carnitine depletion.
Dosing protocols
Common protocols by delivery method. Adjust the curve below to model accumulation in your own cycle.
Injectable
Subcutaneous or intramuscular injection provides superior bioavailability compared to oral supplementation, which is limited to ~15-20% absorption.
| Protocol | Dose | Frequency | Route / duration |
|---|---|---|---|
| Standard Protocol | 50-100mg | Daily | SubQ |
| Advanced Protocol | 100-200mg | Daily | SubQ or IM |
| Pre-Workout | 100-200mg | 30-60 min before exercise | SubQ |
Preparation
You will need
- L-Carnitine lyophilized powder (typically 200mg vial)
- Bacteriostatic water (2.0mL recommended)
- Insulin syringes (29-31 gauge)
- Alcohol swabs
Steps
- Allow vial to reach room temperature
- Clean rubber stopper with alcohol swab
- Add 2.0mL bacteriostatic water for 100mg/mL concentration
- Inject slowly along vial wall
- Gently swirl to dissolve; never shake
- Label with date and store refrigerated at 2-8°C
- Use within 2-4 weeks of reconstitution
Work out the water volume and syringe units in the reconstitution calculator →
Interactions
Pairwise interactions with other compounds you might be cycling — the same data behind the cycle builder's safety check.
Thyroid Hormones
MonitorL-Carnitine may affect thyroid hormone action. Those on thyroid medication should monitor levels.
Anticoagulants
MonitorMay enhance effects of warfarin and similar medications.
Timeline
Typical week-by-week effects reported in clinical and observational data.
- Immediate
Injectable form provides rapid absorption within 30-60 minutes
- Week 1-2
Potential improvements in energy and exercise capacity
- Week 4-8
Cumulative benefits on fat metabolism and recovery
- Week 8-16
Full metabolic optimization when combined with exercise
Safety
Reported adverse effects, contraindications, and what to monitor on cycle.
Common side effects
- Injection site reactions
- Mild nausea
- Body odor (fishy smell at high doses)
Stop signs — stop and seek advice
- Allergic reactions (rare)
- Severe gastrointestinal distress
- Unusual muscle weakness
Contraindications
- Seizure disorders (may lower seizure threshold)
- Hypothyroidism (may affect thyroid function)
- Allergy to carnitine products
Monitoring
- Generally well-tolerated with established safety profile
- FDA-approved for carnitine deficiency
- Monitor thyroid function if on thyroid medication
Quality checks
What a legitimate product looks like, what should give pause, and what should make you stop.
Good signs
- White crystalline powder
- Clear, colorless solution after reconstitution
- Certificate of Analysis with purity testing
Warning signs
- Should dissolve completely without residue
Stop signs — don't use
- Discolored powder
- Cloudy or particulate solution
- Strong unusual odor
References
Primary literature and clinical-trial data informing this entry.
L-Carnitine Supplementation and Exercise
2018
Meta-analysis showing modest benefits of L-carnitine on exercise performance and recovery markers.
Carnitine Metabolism and Function
2012
Comprehensive review of carnitine's role in fatty acid transport and energy metabolism.
Last updated . How this page was sourced is described in the methodology.