Anything that disrupts the normal functioning of the brain can cause a seizure.

Seizures can occur as a sign of a wide variety of medical conditions (e.g., cerebral palsy, Alzheimer’s disease, muscular dystrophy), illnesses (e.g., heatstroke, kidney failure) or due to use of certain medications. Patients should carefully read product labels of all medicated substances (including medicated shampoos) for possible adverse reactions that may include seizures.

However, because of the complex nature of the brain, roughly half of all seizures have no known cause. Unprovoked, repeated seizures may be characteristic of many forms of epilepsy.

Conditions and situations that may provoke seizures include:

• Brain injury. People who have experienced brain trauma, such as severe head injury or stroke, are at a high risk of having a seizure. This usually happens within weeks of the head injury, although some people can have seizures months after the injury. People with head injuries are more likely to have recurrent seizures.
  

  

• High fever. This is an especially common cause of seizures in children, where it is called a febrile seizure. A febrile seizure occurs when a sudden and severe spike in a child’s temperature of 102 degrees Fahrenheit (38.9 degrees Celsius) or more triggers a seizure. Febrile seizures most often affect children between the ages of 6 months and 3 years. In most cases, they are associated with a viral or bacterial infection. Although febrile seizures typically strike when a child’s temperature is rising, they also can occur as the child’s temperature drops. Febrile seizures can be more common in those with a family history of seizures or epilepsy. However, they rarely indicate a child will develop chronic epilepsy.
  
  
• Genetic abnormalities. Some types of seizures have been found to run in families and are thought to be caused by genetic abnormalities. There are many genes that have been linked to seizures. However, only a small proportion of seizure types are believed to develop as a direct result of genetic abnormalities. Instead, studies have shown that people with certain genetic abnormalities are more susceptible to seizures caused by other factors, such as brain trauma.
  
  
• Infections. Certain infections such as meningitis, encephalitis and brain abscess can result in either isolated or recurrent seizures. In some cases, successful treatment of the underlying infection can stop the seizures. However, some infections may cause irreparable damage to cells in the brain.
  
  
• Tumors or brain lesions. Tumors or brain lesions, which can cause pressure to build in the brain, can disrupt the function of neurons. Seizures that are caused by tumors or brain lesions usually begin as partial seizures but may develop into generalized seizures as the tumor or lesion grows. Surgery can sometimes be used to remove the tumor or lesion. Such surgery can reduce or eliminate seizures. The presence of other structural abnormalities in the brain can also cause seizures.
  
  
• Metabolic abnormalities. Seizures can be caused by a wide variety of metabolic problems. This includes diabetes, an electrolyte imbalance, kidney failure and nutritional deficiencies. Abnormal blood sugar levels such as low blood sugar (hypoglycemia) or high blood sugar (hyperglycemia) can provoke seizures.
  
  
• Substance abuse and withdrawal. Heavy drinking or withdrawal after a period of heavy drinking can cause seizures. Both intoxication and withdrawal from alcohol can interfere with the activity of neurons in the brain. Seizures are more likely to occur within six hours to four days of stopping drinking, according to the National Institute on Alcohol Abuse and Alcoholism. The use of certain illegal drugs (e.g., cocaine, amphetamines, heroin) can also cause seizures. Withdrawal symptoms from these drugs can also include seizures.
  
  
• Reactions to certain medications. Some types of medication, such as some chemotherapy drugs, can cause seizures. This may be due to an adverse side effect of the medication, an allergy of the patient, or due to consumption of toxic levels of the medication. Patients should consult their physicians about the risks involved with taking certain medications, whether prescription or over-the-counter remedies.
  
  
• Eclampsia. Eclampsia is a rare condition in pregnant women that results in seizures. It is unclear what causes the seizures, although various factors, including neurological ones, may be involved. Eclampsia is usually accompanied by other complications during pregnancy, such as high blood pressure and excessive weight gain.