Certain drugs can cause seizures, either as a direct side effect, due to overdose, or during withdrawal. This is a medical concern that can affect individuals regardless of their prior medical history. Understanding which substances pose a risk and how they impact the brain is important for prevention and proper response. Drug-induced seizures account for a percentage of new-onset seizures and cases of prolonged seizure activity.
Categories of Drugs Implicated
A wide array of substances, from prescription medications to illicit drugs, can lead to seizures. Prescription drugs are a common cause. Antidepressants, particularly bupropion, account for many drug-induced seizure cases. Antipsychotics, such as clozapine and risperidone, can also induce seizures, especially at higher doses or when multiple antipsychotics are used concurrently. Pain medications like tramadol, and certain antibiotics including cephalosporins and quinolones, have also been linked to seizure activity. This risk often increases when these medications are taken incorrectly or in overdose.
Illicit substances also trigger seizures. Stimulants like cocaine and amphetamines (methamphetamine and MDMA) are known to induce seizures. Synthetic cannabinoids, often called “Spice,” have also been associated with seizures. The sudden cessation of certain substances, particularly alcohol and benzodiazepines, can precipitate withdrawal seizures due to the brain’s adjustment to their absence. Even some over-the-counter medications, such as diphenhydramine (in allergy and sleep aids) and pseudoephedrine (a decongestant), can lower the seizure threshold, especially in overdose situations.
How Drugs Trigger Seizures
Drugs can induce seizures through various physiological mechanisms, primarily by disrupting the balance of electrical activity in the brain. Many substances achieve this by lowering the seizure threshold, making brain cells more excitable and prone to uncontrolled firing. This heightened excitability can lead to widespread electrical activity, impairing brain function.
A common mechanism involves interfering with neurotransmitter balance, specifically the excitatory and inhibitory signals. Drugs can increase excitatory neurotransmitters like glutamate or decrease inhibitory neurotransmitters such as gamma-aminobutyric acid (GABA). For example, some antibiotics can inhibit GABA receptor binding, leading to increased neuronal excitability. Conversely, withdrawal from drugs that enhance GABA activity, like benzodiazepines and alcohol, can result in a sudden drop in GABA levels, triggering seizures.
Some drugs can also directly damage brain cells (neurotoxicity), which disrupts normal brain activity and elevates seizure risk. Additionally, certain drugs can cause metabolic disturbances, such as electrolyte imbalances (e.g., low sodium levels) or abnormal blood sugar levels, which can further affect brain function and precipitate seizures.
Factors Increasing Seizure Risk
Several individual and situational factors can increase a person’s susceptibility to drug-induced seizures. The dosage and administration method of a drug are important; higher doses, rapid administration, or incorrect use can elevate the risk. For instance, the seizure risk associated with some antipsychotics and antidepressants is dose-dependent.
Pre-existing medical conditions also contribute to increased vulnerability. Individuals with a history of epilepsy, previous seizures, brain injury, stroke, or other neurological disorders are at a higher risk. Conditions affecting organ function, such as kidney or liver disease, can impair drug metabolism and excretion, leading to higher drug concentrations in the body and an increased seizure risk.
Polypharmacy, the concurrent use of multiple medications, can also increase risk due to potential drug interactions that cumulatively lower the seizure threshold or alter drug levels. Extremes of age, particularly infants and the elderly, may have different metabolic rates and sensitivities to drugs, making them more susceptible. Genetic predispositions can also influence an individual’s likelihood of experiencing drug-induced seizures.
Responding to a Drug-Induced Seizure
If someone experiences a drug-induced seizure, immediate actions can help ensure their safety. Clear the area around the person to prevent injury from sharp or hard objects. Gently ease the person to the ground if they are falling and turn them onto one side, with their mouth angled towards the ground, to help keep their airway clear and prevent aspiration. Place something soft and flat, like a jacket, under their head to protect it.
Time the seizure. Do not attempt to restrain the person’s movements or put anything into their mouth, as this can cause injury to both the person having the seizure and the helper.
Most drug-induced seizures are self-limiting, but emergency medical attention is necessary if the seizure lasts longer than 5 minutes, if repeated seizures occur without recovery of consciousness, or if the person has difficulty breathing or is injured during the seizure. Medical help should also be sought for a first-time seizure. When medical professionals arrive, providing a history of all substances taken, including prescription medications, over-the-counter drugs, and illicit substances, is important for accurate diagnosis and treatment.