L-Arginine for Health & Longevity - Quick Reference Sheet

L-Arginine for Health & Longevity

Created on 09/05/2026 – Quick Reference based on Evidence Review created using AI4L / Opus 5 – Audit

An amino acid the body already makes, taken to feed the pathway blood vessels use to relax. Blood pressure falls modestly; erectile function of mild to moderate severity improves; early use lowers the dangerous blood-pressure disorder of pregnancy. Gut upset sets the practical dose limit. Two harm signals: deaths after recent heart attack, and rising inflammation in older users. (Full Review)

Protocol

Standard dose range
3–6 g daily
5 g daily for erectile function. 4 g daily is the minimum effective amount, with no further gain above 9 g.
Split dosing rather than a single bolus
2–3 doses of 1.5–3 g
Maintains a raised plasma level across the day and keeps each dose below the gastrointestinal threshold.
Best time of day
Empty stomach
At least 30 minutes before food. Pre-exercise dosing uses 0.15 g per kg body weight, 60–90 minutes beforehand.
Time to effect
Blood pressure
2–4 weeks
Usually complete by week 8.
Erectile function
4–12 weeks
The window over which trials measured outcomes.
Wound healing
2–8 weeks
Recorded over continuous dosing.

Benefits

Contraindications
  • Organic nitrates (nitroglycerin, isosorbide mononitrate)
  • Recent myocardial infarction (heart attack within the past 6 months)
  • Inherited urea-cycle disorders (argininosuccinate synthase, argininosuccinate lyase or ornithine transcarbamylase deficiency)
  • Decompensated cirrhosis (Child-Pugh Class C)
  • Advanced chronic kidney disease (filtration rate below 30 mL/min/1.73 m²) or established hyperkalaemia above 5.5 mmol/L
  • Severe heart failure (New York Heart Association Class IV) on nitrate therapy
  • Guanidinoacetate methyltransferase deficiency and other inborn errors of creatine synthesis
  • Active sepsis or septic shock
Key Interactions
  • Blood-pressure-lowering drugs (enalapril, ramipril, losartan, valsartan, amlodipine, hydrochlorothiazide)
  • Phosphodiesterase type 5 inhibitors (sildenafil, tadalafil)
  • Potassium-raising drugs (spironolactone, amiloride, ACE inhibitors, trimethoprim)
  • Antidiabetic drugs (insulin, sulfonylureas such as glipizide)
  • Over-the-counter painkillers and decongestants (ibuprofen and other NSAIDs, pseudoephedrine, phenylephrine)
  • Over-the-counter agents (nitric-oxide pre-workout blends, potassium-based salt substitutes)
  • Supplement interactions with additive blood-pressure lowering (citrulline, dietary nitrate, garlic, hawthorn, taurine, magnesium, omega-3 fatty acids, ginseng, Pycnogenol)
  • Lysine and other cationic amino acids (ornithine, histidine)
  • Other interventions (vasodilating sauna protocols, alcohol, post-exercise hypotension)

Risk & Side Effects

  • High: Gastrointestinal intolerance
  • Medium: Excess mortality after recent myocardial infarction; rise in C-reactive protein in older adults and cancer patients
  • Low: Symptomatic hypotension; acute pancreatitis; hyperkalaemia at high doses; oral and oesophageal irritation
  • Speculative: Herpes simplex reactivation; support of arginine-dependent tumours; airway symptom aggravation in asthma

Monitoring

Marker Target Why
Home blood pressure, seated Below 120/75 mmHg The primary measurable effect
Plasma arginine to asymmetric dimethylarginine ratio Above 100 (molar ratio); higher is better Estimates substrate available relative to the natural blocker of nitric oxide production
High-sensitivity C-reactive protein Below 1.0 mg/L Detects the inflammatory rise recorded in older users and in cancer
Fasting triglycerides Below 80 mg/dL The one blood fat that shifts on arginine
Serum potassium 4.0–4.5 mmol/L Arginine drives potassium out of cells
Serum creatinine and estimated glomerular filtration rate Creatinine 0.7–1.0 mg/dL in men and 0.6–0.9 in women; filtration rate above 90 mL/min/1.73 m² Establishes kidney capacity before a sustained nitrogen load
Fasting glucose and glycated haemoglobin Glucose 75–86 mg/dL; glycated haemoglobin 4.8–5.3% Arginine stimulates insulin release
Blood urea nitrogen 10–16 mg/dL Arginine feeds the urea cycle directly
Plasma arginine (standalone) No established target; track the change from the individual's own pre-supplement baseline Confirms the dose is actually being absorbed

Cadence: Full baseline panel before the first dose; home blood pressure at week 2 and week 4; potassium and creatinine at week 4 on a potassium-retaining drug; inflammation marker and lipid panel at week 12; then every 6–12 months once values are stable.

Qualitative Assessment

  • Morning and afternoon energy, rated on a simple 1–10 scale at a fixed time each day
  • Exercise session quality: perceived effort at a fixed workload, and time to fatigue
  • Peripheral warmth in hands and feet, and cold-induced colour changes
  • Erectile quality and morning erections, where relevant
  • Bowel habit, stool consistency and abdominal bloating, as the earliest signal of dose intolerance
  • Lightheadedness on standing, as the earliest signal of excessive pressure lowering
  • Wound and skin healing speed, where healing is the reason for use