A seizure threshold is the balance between excitatory and inhibitory forces in the brain which affects how susceptible one is to seizure

Seizure

An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...

s. Those diagnosed with epilepsy

Epilepsy

Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...

 or certain other neurological conditions are vulnerable to sudden new seizures if the threshold is upset, and so must be especially careful and compliant with their therapeutic drug regimen, if they must use anticonvulsant

Anticonvulsant

The anticonvulsants are a diverse group of pharmaceuticals used in the treatment of epileptic seizures. Anticonvulsants are also increasingly being used in the treatment of bipolar disorder, since many seem to act as mood stabilizers, and in the treatment of neuropathic pain. The goal of an...

s. Drugs such as the antidepressant

Antidepressant

An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...

 and nicotinic antagonist

Nicotinic antagonist

A nicotinic antagonist is a type of anticholinergic that inhibits the action at nicotinic acetylcholine receptors. These compounds are mainly used for peripheral muscle paralysis in surgery, but some centrally acting compounds such as bupropion, mecamylamine, and 18-methoxycoronaridine block...

 bupropion

Bupropion

Bupropion is an atypical antidepressant and smoking cessation aid. The drug is a non-tricyclic antidepressant and differs from most commonly prescribed antidepressants such as SSRIs, as its primary pharmacological action is thought to be norepinephrine-dopamine reuptake inhibition...

 (Wellbutrin, Zyban) and the analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 tramadol

Tramadol

Tramadol hydrochloride is a centrally acting synthetic opioid analgesic used in treating moderate pain. The drug has a wide range of applications, including treatment for restless legs syndrome and fibromyalgia...

(Ultram, Ultram ER, Ultracet) can lower the seizure threshold. So can other factors, including, among many others: exposure to neon or laser flashing lights, lengthy periods of fasting, malnutrition, starvation, lengthy periods of high stress and/or fear, fatigue and exhaustion (i.e., from lack of sleep and/or rest), uncontrolled diabetes, other endocrine and/or metabolic irregularities (like electrolyte or hormonal imbalances), cancer, and certain disorders of the nervous, cardiovascular, and gastrointestinal systems.