Convulsion, is it dangerous?

Not necessarily: A seizure is an abnormal spread of electrical activity in the brain. It can cause a lapse in consciousness & loss of muscle control, which exposes folks to danger in high risk situations. Seizures can also cause brain injury and sudden death when uncontrolled. Seeing a doctor to determine the cause and how best to control the convulsion/seizure is of utmost importance.

Yes: More than the occurence of the seizure is the circumstance in which it occurs. For instance while driving, walking down stairs, crossing a street with traffic, swimming alone or in a situation in which you may fall a distance.