Citrulline / L-Citrulline for Erectile Dysfunction
Citrulline shows a faint early signal for mild erectile dysfunction, but the evidence is too thin and low-quality to recommend it as a treatment. It is not a substitute for proven options, and combining it with prescription ED drugs may be dangerous.
Why this grade7-layer evidence engine
The grade is Weak (Tier C) because the entire human case rests on three small, low-quality RCTs. The only trial of citrulline alone (Cormio 2011, PMID 21195829) enrolled just 24 men, ran four weeks, and was open-label rather than double-blind, so a placebo effect cannot be ruled out despite its eye-catching result (50% of men improved from mild ED to normal vs 8.3% on placebo).
The two later randomized trials (PMID 30150102 and PMID 33151048) were double-blind but tested citrulline inside multi-ingredient formulas (with resveratrol, and additionally Testofen and caffeine), so any benefit cannot be attributed to citrulline itself. One even found no significant change in erection hardness (p=0.79). No meta-analysis or systematic review exists, and doses were far below the levels typically studied.
Authorities reinforce the caution. The EU's EFSA twice issued unfavourable opinions on citrulline health claims, the US FDA treats it only as a dietary supplement with no approved claim, and the UK NHS and WHO do not address it. Mayo Clinic notes ED supplements are far less studied than prescription medicines and advises consulting a clinician first. Importantly, taking citrulline with PDE5 inhibitors (e.g. Viagra, Cialis) carries a risk of dangerously low blood pressure.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.524
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 無高階證據可裁決
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status