A complex partial seizure occurs when epileptic activity spreads to both temporal lobes in the brain. A complex partial seizure often occurs after a simple partial seizure of temporal lobe origin.

A complex partial seizure does not involve convulsions, but consciousness is impaired. Someone experiencing one will no longer respond to questions after the seizure starts. A complex partial seizure often begins with a blank look or empty stare. They will appear unaware of their surroundings and may seem dazed. The seizure may progress to include chewing movements, uncoordinated activity, or sometimes performing meaningless bits of behaviour which appear random and clumsy. These automatisms may include actions such as picking at their clothes, trying to remove them, walking about aimlessly, picking up things, or mumbling. Someone experiencing a complex partial seizure may become frightened and try to run and struggle. Following the seizure, there will be no memory of it.

A complex partial seizure usually lasts about 2 to 4 minutes. It may be followed by a state of confusion lasting longer. Once the pattern of seizures is established, it will usually be repeated with each subsequent seizure.

Complex partial seizures sometimes resist anti-convulsant medication.