Garlic for Common Cold
There is not enough good-quality evidence to show that garlic supplements prevent or shorten the common cold. The single supportive trial is too small and methodologically flawed to be trusted, and major health authorities do not endorse garlic for this use.
Why this grade7-layer evidence engine
The entire case rests on one small randomized trial (Josling 2001, n=146; PMID 11697022), which reported far fewer colds in the garlic group (24 vs 65) and shorter symptoms. But its results are unreliable: the strong garlic odour likely broke the blinding so participants could guess their group, all outcomes were self-reported with no virological confirmation, and the funding source was never disclosed.
A Cochrane systematic review (Lissiman 2014; PMID 25386977) screened the literature and found this was the *only* eligible RCT, concluding the evidence is insufficient to draw conclusions. No qualifying trials have appeared since, so the evidence base has not improved in over a decade. This is why the grade lands at the bottom tier with low confidence rather than a positive verdict.
Health authorities reinforce this caution. The US FDA rejected garlic disease claims as not based on a deliberative review of the scientific evidence, and the UK NHS does not address garlic for colds at all. The WHO monograph endorses garlic only as an adjunct for cholesterol and mild hypertension, not for colds, while Harvard Health and other clinics rate the cold claim as cautious-to-against. Garlic supplements can also thin the blood and interact with anticoagulants such as warfarin.
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 = 0.361
- 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