Zinc gluconate lozenges for treating the common cold. A randomized, double-blind, placebo-controlled study.
BACKGROUND
The common cold is one of the most frequent human illnesses and is responsible for substantial morbidity and economic loss. No consistently effective therapy for the common cold has been well documented, but evidence suggests that several possible mechanisms may make zinc an effective treatment.


OBJECTIVE
To test the efficacy of zinc gluconate lozenges in reducing the duration of symptoms caused by the common cold.


METHODS
Randomized, double-blind, placebo-controlled study.


METHODS
Outpatient department of a large tertiary care center.


METHODS
100 employees of the Cleveland Clinic who developed symptoms of the common cold within 24 hours before enrollment.


METHODS
Patients in the zinc group (n = 50) received lozenges (one lozenge every 2 hours while awake) containing 13.3 mg of zinc from zinc gluconate as long as they had cold symptoms. Patients in the placebo group (n = 50) received similarly administered lozenges that contained 5% calcium lactate pentahydrate instead of zinc gluconate.


METHODS
Subjective daily symptom scores for cough, headache, hoarseness, muscle ache, nasal drainage, nasal congestion, scratchy throat, sore throat, sneezing, and fever (assessed by oral temperature).


RESULTS
The time to complete resolution of symptoms was significantly shorter in the zinc group than in the placebo group (median, 4.4 days compared with 7.6 days; P < 0.001). The zinc group had significantly fewer days with coughing (median, 2.0 days compared with 4.5 days; P = 0.04), headache (2.0 days and 3.0 days; P = 0.02), hoarseness (2.0 days and 3.0 days; P = 0.02), nasal congestion (4.0 days and 6.0 days; P = 0.002), nasal drainage (4.0 days and 7.0 days; P < 0.001), and sore throat (1.0 day and 3.0 days; P < 0.001). The groups did not differ significantly in the resolution of fever, muscle ache, scratchy throat, or sneezing. More patients in the zinc group than in the placebo group had side effects (90% compared with 62%; P < 0.001), nausea (20% compared with 4%; P = 0.02), and bad-taste reactions (80% compared with 30%; P < 0.001),


CONCLUSIONS
Zinc gluconate in the form and dosage studied significantly reduced the duration of symptoms of the common cold. The mechanism of action of this substance in treating the common cold remains unknown. Individual patients must decide whether the possible beneficial effects of zinc gluconate on cold symptoms outweigh the possible adverse effects.
Mossad
S B
SB
Cleveland Clinic Foundation, Ohio, USA.
Macknin
M L
ML
Medendorp
S V
SV
Mason
P
P
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D003139:Common Cold / Q000188:drug therapy*; D003371:Cough / Q000188:drug therapy; D004311:Double-Blind Method; D005260:Female; D005334:Fever / Q000188:drug therapy; D005942:Gluconates / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D006261:Headache / Q000188:drug therapy; D006685:Hoarseness / Q000188:drug therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009132:Muscles; D010146:Pain / Q000188:drug therapy; D010612:Pharyngitis / Q000188:drug therapy; D012220:Rhinitis / Q000188:drug therapy; D012912:Sneezing; D013997:Time Factors; D016896:Treatment Outcome; D015032:Zinc / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*
D005942:Gluconates; D015032:Zinc; C030691:gluconic acid