The aerosol can shoots bursts of atomized capsaicin (a red pepper derivative) up to eight metres, though the spray is most effective at short range. Bear pepper spray causes the membranes of the eyes, nose and lungs of a bear to swell and the result is a nearly total, yet temporary, loss of sight and severe restriction of breathing.
The inflammatory properties of the bear spray will affect humans in a similar way as it does bears. A person contaminated with bear spray will experience the mucous membranes of the eyes, nose and lungs to swell and be irritated. The eyes will involuntarily close and tear, the nose will run profusely coughing will result.
It may take up to 15 – 20 minutes before relief from the symptoms are felt.