Certain medications and substances can trigger seizures, even in individuals with no prior history of epilepsy. These drug-induced seizures result from various interactions within the brain, disrupting its normal electrical activity. Understanding which substances pose a risk and their underlying mechanisms is important.
Medications and Substances That Can Cause Seizures
Many drugs, from prescription to illicit substances, can lead to seizures. Prescription drugs are a frequent cause, including antidepressants like bupropion and tricyclic antidepressants. Antipsychotics, certain pain medications such as tramadol, antibiotics like isoniazid, and stimulants can also induce seizures.
Illicit substances are also linked to seizures. Stimulants like cocaine, amphetamines, and MDMA (ecstasy) are known to cause seizures. Synthetic cannabinoids are also associated with this risk.
Over-the-counter (OTC) medications, especially at high doses, can also lower the seizure threshold. Examples include diphenhydramine (in allergy and sleep aids) and decongestants like pseudoephedrine. Withdrawal from substances like alcohol, benzodiazepines, and opioids can also precipitate seizures, particularly with prolonged or heavy use.
How Drugs Can Trigger Seizures
Drugs can induce seizures by disrupting the balance of electrical activity in the brain. Seizures occur when there is an imbalance between excitatory and inhibitory signals in brain cells. Many substances can lower the “seizure threshold,” making brain cells more excitable and prone to uncontrolled firing.
This disruption often involves neurotransmitters, the brain’s chemical messengers. Some drugs can increase excitatory neurotransmitters like glutamate or decrease inhibitory ones such as gamma-aminobutyric acid (GABA). An excess of excitatory signals or a lack of inhibitory ones can lead to the hypersynchronous neuronal discharge characteristic of a seizure. Drugs may also cause seizures through neurotoxicity, metabolic disturbances, or by altering cerebral blood flow and oxygen levels.
Factors Increasing Seizure Risk
Several factors increase susceptibility to drug-induced seizures. The dosage and rate of administration play a role; higher doses or rapid changes in medication levels increase the risk. Individual susceptibility varies, with genetic predispositions or pre-existing neurological conditions like epilepsy increasing vulnerability.
Drug interactions, especially polypharmacy, can elevate seizure risk by altering drug metabolism or combining effects that lower the seizure threshold. Age is another factor, as very young children and the elderly have increased susceptibility. Underlying medical conditions, such as kidney or liver dysfunction, can impair drug metabolism and excretion, leading to higher drug concentrations and increased risk. Electrolyte imbalances or other metabolic disturbances also contribute to this risk.
What to Do During a Drug-Induced Seizure
If someone is experiencing a drug-induced seizure, focus on ensuring their safety. Remain calm and gently guide the person to the ground, moving dangerous objects away. Cushion their head with something soft (e.g., jacket or pillow) to protect against injury.
Do not restrain the person or put anything into their mouth, as this can cause injury. Once the shaking stops, gently turn the person onto their side to keep their airway clear and prevent choking. Time the seizure if possible; most seizures last only a few minutes.
Call emergency services if:
- The seizure lasts longer than five minutes.
- Another seizure occurs without full recovery.
- The person has trouble breathing or waking up afterward.
- They are injured during the seizure.
Emergency medical attention is also warranted for a first-time seizure, or if the person is pregnant, diabetic, or has other life-threatening conditions. Seeking medical attention afterward is important for proper diagnosis and management.