Baseline characteristics
| Placebo | Zinc lozenge | |
| Total | 42 | 45 |
| Age, mean (SD) | 48 y (9 y) | 46 y (10 y) |
| Males | 3 (7%) | 6 (13%) |
| Contact with children | 32 (76%) | 32 (71%) |
| ≥2 colds per winter | 23 (55%) | 24 (53%) |
| Sick leaves for colds on the previous winter | 29 (69%) | 27 (60%) |
| Colds usually long | 28 (67%) | 28 (62%) |
| Regular asthma | 4 (10%) | 6 (13%) |
| Asthma medication for some previous colds | 14 (33%) | 12 (27%) |
| Sinusitis within 5 years | 19 (45%) | 9 (20%) |
| Bronchitis within 5 years | 12 (29%) | 10 (22%) |