Most cold medicines contain at least one ingredient that can lower your seizure threshold, so choosing the right product requires reading labels carefully. The safest approach is to treat each symptom individually with single-ingredient products rather than reaching for an all-in-one cold remedy, which often bundles together several risky ingredients in one dose.
Ingredients That Can Lower Your Seizure Threshold
The biggest concerns in cold medicine fall into three categories: decongestants, first-generation antihistamines, and certain cough suppressants. Many popular multi-symptom products combine two or even all three of these, which compounds the risk.
Pseudoephedrine and phenylephrine are the decongestants found in most cold medicines. Pseudoephedrine is a central nervous system stimulant that increases the release of norepinephrine and dopamine in the brain, which can alter neuronal excitability. Case reports document seizures in people with no prior history of epilepsy after taking even small doses. In one French study, 15 cases of convulsions were linked to oral decongestants containing pseudoephedrine. For someone who already has epilepsy, the risk is higher. Phenylephrine appears somewhat safer in practice, but reports of seizures exist for it too.
Diphenhydramine (the active ingredient in Benadryl and many “nighttime” cold formulas) and chlorpheniramine are first-generation antihistamines that cross into the brain and directly affect brain wave activity. Research shows these older antihistamines can induce symptomatic seizures, alter seizure thresholds in people with existing seizure susceptibility, and change resting brain wave patterns. They’re a common trigger of acute symptomatic seizures. If you take lamotrigine, chlorpheniramine also amplifies side effects like dizziness, drowsiness, and impaired coordination.
Dextromethorphan (the “DM” in many cough syrups) has a complicated profile. At normal doses, its mechanism of action actually has some theoretical antiseizure properties. But a small clinical study found a nonsignificant trend toward increased complex partial seizures, and in overdose, dextromethorphan clearly precipitates seizures. It can also cause drowsiness and confusion that stack on top of similar side effects from seizure medications. If you take clobazam, it may increase dextromethorphan levels in your blood. The American Epilepsy Society advises patients to consider avoiding combination products containing dextromethorphan and to read OTC labels carefully.
Caffeine shows up in some cold and headache formulas (like Excedrin). A systematic review of 105 studies found that caffeine can trigger seizures in people with and without epilepsy, and even a single high dose can lower the seizure threshold.
Safer Options for Each Symptom
Rather than taking one pill that covers everything, pick products that target only the symptom bothering you most. This lets you avoid the ingredients you don’t need.
For fever and body aches: Acetaminophen (Tylenol) is generally the safest choice. The Epilepsy Foundation specifically names it as probably the safest pain reliever for people with epilepsy. One thing to know: if you take lamotrigine, high doses of acetaminophen (2,700 to 4,000 mg daily over several days) can reduce your lamotrigine levels. If your lamotrigine level already runs near the low end of the therapeutic range, this could matter. Keep your total acetaminophen under 4,000 mg per day, and under 3,000 mg if you’re over 65. Ibuprofen is another option, though it can slightly lower valproic acid levels and raise phenytoin levels, so it needs more care depending on which seizure medication you take.
For a stuffy nose: Saline nasal spray or a saline rinse carries zero seizure risk and is often surprisingly effective. Nasal steroid sprays (like fluticasone) work locally in the nose and don’t significantly enter your bloodstream or affect brain activity. These are far better choices than oral decongestants.
For a runny nose or sneezing: Second-generation antihistamines like cetirizine (Zyrtec) or loratadine (Claritin) are preferred over first-generation options. They don’t cross into the brain as readily, which means less impact on brain wave activity and seizure threshold. There are rare reports of seizure induction with second-generation antihistamines, but they carry substantially less risk than diphenhydramine or chlorpheniramine.
For a cough: Honey (for adults and children over one year) and throat lozenges are the simplest options with no seizure concerns. If you need something stronger, talk to your pharmacist about whether dextromethorphan is appropriate given your specific seizure medication. The interaction profile varies depending on what you take.
Why Combination Products Are Risky
Products marketed as “cold and flu” relief, especially the nighttime versions, typically combine acetaminophen with a decongestant, a first-generation antihistamine, and sometimes dextromethorphan and caffeine. One documented case involved a 31-year-old woman with no seizure history who developed nonconvulsive status epilepticus after taking two types of cold medications containing pseudoephedrine, dextromethorphan, acetaminophen, and chlorpheniramine for 10 days. Another case described a generalized seizure in an older adult after a small dose of pseudoephedrine combined with caffeine.
The layering effect matters. Each ingredient on its own may pose a modest risk, but combining a stimulant decongestant with a brain-active antihistamine and a cough suppressant that interacts with your seizure medication creates a situation where the cumulative effect on your brain’s excitability is unpredictable.
Herbal Cold Remedies to Watch Out For
Natural doesn’t mean safe for epilepsy. Herbal products containing ephedrine (from ephedra or ma huang) and caffeine (from guarana, cola nut, or maté) can worsen seizures, especially in combination. Ginkgo and ginseng may also increase seizure risk, though the evidence is mostly anecdotal. St. John’s wort, sometimes used for immune support, can alter how your body processes seizure medications and may also affect the seizure threshold directly. Essential oils from many plants contain compounds that can provoke seizures. Evening primrose oil and borage oil have mixed evidence for lowering the seizure threshold as well.
Echinacea and elderberry, two of the most popular cold-season supplements, don’t have strong evidence linking them to seizures, but they also haven’t been studied well in people with epilepsy. The bigger risk with any herbal supplement is that it could change how your liver processes your seizure medication, raising or lowering drug levels without you realizing it.
How to Read the Label
Before buying any cold product, flip the box over and look at the “Active Ingredients” section. The names to scan for are pseudoephedrine, phenylephrine, diphenhydramine, chlorpheniramine, dextromethorphan, and caffeine. If you see any of these, either choose a different product or check with your pharmacist about whether the specific ingredient interacts with your seizure medication.
Also check whether liquid formulations contain alcohol, which can increase drowsiness when combined with seizure medications and may independently affect seizure control. Look for alcohol-free versions when choosing syrups.
Your pharmacist is one of your best resources here. They can see your full medication list and flag interactions in real time, which is especially useful since the interaction profile changes depending on whether you take lamotrigine, valproic acid, phenytoin, carbamazepine, or another seizure medication. A five-minute conversation at the pharmacy counter can save you from an avoidable risk.