Polypharmacy means taking multiple medicines at the same time. It is especially common in older adults and people with several long-term conditions. In epilepsy, polypharmacy can affect seizure control, side effects, adherence and the concentrations of both antiseizure and non-epilepsy medicines.
Why epilepsy is particularly vulnerable to interactions
Some antiseizure medicines induce or inhibit liver enzymes and transport proteins, changing the concentrations of other drugs.
Other medicines can change antiseizure drug concentrations or lower the seizure threshold.
Polypharmacy is not automatically inappropriate
A person may genuinely need several medicines for epilepsy, cardiovascular disease, diabetes, mental health, pain or other conditions.
The problem is not simply the number of prescriptions. It is whether each medicine still has a clear purpose and whether the combination remains safe.
Older enzyme-inducing antiseizure medicines
Medicines such as carbamazepine, phenytoin and phenobarbital can interact with many other treatments through hepatic enzyme induction.
Potential consequences include reduced effectiveness of some anticoagulants, hormonal contraceptives, cardiovascular drugs and other therapies.
The reverse interaction also matters
Antibiotics, antifungals, psychiatric medicines and other treatments can alter antiseizure medication concentrations.
Valproate, lamotrigine and carbamazepine are examples where clinically important interactions can occur through different mechanisms.
Falls and cognition can reveal cumulative burden
Several medicines may each have modest sedating or balance effects that become clinically important when combined.
Dizziness, confusion, fatigue or falls should therefore trigger review of the whole medication list rather than automatically blaming epilepsy.
Kidney and liver function change the equation
Ageing and illness can reduce drug clearance. A dose that was tolerated years earlier may become excessive after renal or hepatic function changes.
Some medicines require dose adjustment according to kidney function or measured drug concentrations.
Medication review should be coordinated
Neurology, primary care, pharmacy and other specialists may each prescribe part of the medication list.
Regular reconciliation helps identify duplication, obsolete prescriptions, interaction risk and medicines that were intended to be temporary.
Do not simplify treatment by suddenly stopping it
Deprescribing can be valuable, but antiseizure medicines and several other drugs can cause harm if stopped abruptly.
Changes should be planned around the person’s seizure history, indication, interaction profile and clinical priorities.
Related reading
Sources and further reading
- Antiseizure medications in older adults: pharmacology, safety and tolerability, 2026
- ILAE Task Force review: management of epilepsy in older adults
Evidence checked: September 2026.