From the Guidelines
Benadryl (diphenhydramine) should be used with caution in patients with epilepsy, as it may lower the seizure threshold and increase the risk of seizures, and its use is not recommended as a first-line treatment for these patients. The medication works by blocking histamine receptors but also has anticholinergic effects that can affect the central nervous system 1. If Benadryl must be used in a patient with epilepsy, it should be at the lowest effective dose and preferably for short-term use only. Patients should be monitored for any increase in seizure activity, especially when starting the medication. Non-sedating antihistamines like loratadine (Claritin) or cetirizine (Zyrtec) are generally safer alternatives for allergy symptoms in epilepsy patients as they have less CNS penetration and minimal impact on seizure threshold.
Some studies suggest that diphenhydramine may have a negative impact on seizure control, although the evidence is not conclusive 1. However, given the potential risks, it is essential to exercise caution when using Benadryl in patients with epilepsy. The most recent clinical policy on the management of adult patients presenting to the emergency department with seizures, published in 2024, does not specifically address the use of Benadryl in epilepsy patients, but it emphasizes the importance of careful evaluation and management of seizures in the emergency department 1.
In terms of management, the clinical policy recommends the use of benzodiazepines as first-line treatment for recurrent seizures, with second-line treatment including agents such as phenytoin, levetiracetam, and valproic acid 1. The policy also highlights the importance of identifying and treating underlying medical conditions that may be contributing to the seizures.
In summary, while Benadryl may be used in patients with epilepsy, it should be used with caution and under close monitoring due to the potential risks of lowering the seizure threshold and increasing the risk of seizures. Non-sedating antihistamines are generally safer alternatives, and patients should be consulted with their neurologist before adding Benadryl to their medication regimen, especially if they have poorly controlled epilepsy or are on multiple anti-seizure medications.
From the Research
Safety of Administering Benadryl to Patients with Epilepsy
- The safety of administering Benadryl (diphenhydramine) to patients with epilepsy is a concern due to its potential to induce seizures 2.
- Diphenhydramine is a first-generation antihistamine, and there is evidence that first-generation H1-antagonists can provoke convulsions in healthy children as well as epileptic patients 2.
- While benzodiazepines are commonly used to treat seizures and status epilepticus 3, 4, there is no direct evidence to suggest that Benadryl is safe for use in patients with epilepsy.
- In fact, a study on drug-induced seizures suggests that antihistamines, including Benadryl, can cause seizures as a result of inadequate inhibitory influences or excessive excitatory stimulation 4.
- Another study on the prophylactic use of antiepileptic drugs in patients scheduled for neurosurgery notes that antiepileptic drugs can have diverse mechanisms of action, but does not provide guidance on the use of Benadryl in patients with epilepsy 5.
- A review of antidepressants in epilepsy suggests that some antidepressants can lower the risk of triggering seizures, but does not mention Benadryl as a safe option for patients with epilepsy 6.
- A case study on seizures induced by desloratadine, a second-generation antihistamine, recommends caution when treating epileptic patients with histamine H(1)-antagonists, including second- and third-generation drugs 2.