Seizures are sometimes caused by medicines. Regular doses of nonprescription and prescription medicines can cause seizures in a person who is especially sensitive to the medicines. A seizure may be a sign of an allergic reaction to a medicine. Overuse or overdosage of many medicines also can cause seizures. You may have a seizure if you abruptly stop taking a prescription medicine.

Prescription medicines that can cause seizures include:

• Antibiotics, such as penicillin and isoniazid (for example, Nydrazid).
• Antidepressants, such as amitriptyline and doxepin.
• Antipsychotic medicines, such as haloperidol and chlorpromazine.
• Asthma medicines, such as aminophylline, theophylline, and terbutaline.
• Lithium.
• Local anesthetics, such as procaine and lidocaine, especially if they also contain epinephrine.

Nonprescription medicines that can cause seizures include:

• Antihistamines, such as diphenhydramine (for example, Benadryl).
• Cold medicines and decongestants.
• Aspirin.

Illegal drugs that can cause seizures include:

• Cocaine.
• Methamphetamines.
• Heroin.
• Designer or "club" drugs, such as Ecstasy.

If you think that your seizure may have been caused by a medicine, call your doctor immediately to discuss this serious side effect. Do not take another dose of the medicine.