Epilepsy is a very common condition (usually because the patient hasn’t taken their medication) in which the patient may experience a loss of consciousness with initial whole body spasm followed by rhythmic contraction of all the body muscles. The patient will usually have a loss of bladder control.
Management of a patient having a seizure is to turn them on their side and protect the head from injury. Allowing the patient to seize on their back may cause a severe head injury.
Allow the seizure to pass and then monitor the patient on their side while you wait for an ambulance.