Background
Garlic is alleged to have antimicrobial and antiviral properties that relieve the common cold, among other beneficial effects. There is
widespread usage of garlic supplements. The common cold is associated with significant morbidity and economic consequences. On
average, children have six to eight colds per year and adults have two to four.
Objectives
To determine whether garlic (allium sativum) is effective for either the prevention or treatment of the common cold, when compared
to placebo, no treatment or other treatments.
Search methods
We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 4), which includes the Cochrane Acute
Respiratory Infections Group Specialised Register, OLDMEDLINE (1950 to 1965), MEDLINE (January 1966 to November week 3,
2011), EMBASE (1974 to December 2011) and AMED (1985 to December 2011).
Selection criteria
Randomised controlled trials of common cold prevention and treatment comparing garlic with placebo, no treatment or standard
treatment.
Data collection and analysis
Two review authors independently reviewed and selected trials from searches, assessed and rated study quality and extracted relevant
data.
Main results
Of the six trials identified as potentially relevant fromour searches, only one trialmet the inclusion criteria. This trial randomly assigned
146 participants to either a garlic supplement (with 180 mg of allicin content) or a placebo (once daily) for 12 weeks. The trial reported
24 occurrences of the common cold in the garlic intervention group compared with 65 in the placebo group (P < 0.001), resulting
in fewer days of illness in the garlic group compared with the placebo group (111 versus 366). The number of days to recovery from
an occurrence of the common cold was similar in both groups (4.63 versus 5.63). Only one trial met the inclusion criteria, therefore