1. A temporary loss of consciousness which sometimes causes provoked convulsive seizures as a result of the intensity of the carotid sinus reflex when pressure increases in one or both carotid sinuses.
2. Intense hypotension (low blood pressure) and bradycardia (abnormally slow heartbeat) following carotid sinus stimulation, resulting in dizziness, fainting or convulsions, and occasionally other neurologic symptoms.

Syncope (spontaneous loss of consciousness caused by insufficient blood to the brain) when assuming the standing position.

Fainting as a result of a coughing spell, caused by persistent increased intrathoracic pressure (within the cavity of the chest) diminishing venous return to the heart (blood returning to the heart via the great veins and coronary sinus), thus lowering cardiac output.

It most often occurs in heavy-set male smokers who have chronic bronchitis.