Diphenhydramine With Bupropion (Wellbutrin)
Diphenhydramine is not listed as an absolute contraindication with bupropion, but concurrent use can increase diphenhydramine exposure/effects. [1]
Bupropion increases seizure risk through lowering the seizure threshold, so increased CNS effects and dose-related toxicity from diphenhydramine can be clinically important. [2], [3]
Drug-Interaction Considerations
Drug-interaction resources list a pharmacokinetic/pharmacodynamic interaction in which bupropion may increase blood levels and effects of diphenhydramine. [1]
Diphenhydramine can cause anticholinergic toxicity and serious adverse events with excessive dosing, including seizures. [3]
Safety When Diphenhydramine Is Used
Short-term, single-dose, standard over-the-counter diphenhydramine use is generally approached as “caution” rather than prohibition when seizure risk factors are absent. [1], [2], [3]
Increased sedation, dizziness, and impaired cognition can occur from diphenhydramine, which can be more problematic when bupropion is also being taken. [1]
Seizure-Risk Nuances With Bupropion
Bupropion should be avoided in patients with a seizure disorder and is contraindicated in patients with current or prior diagnosis of anorexia nervosa or bulimia. [2]
Additional conditions and concomitant agents that lower seizure threshold increase seizure risk with bupropion and should increase caution with diphenhydramine exposure if overdose or other proconvulsant factors occur. [2], [3]
Practical Risk-Reduction Approach
Diphenhydramine dosing should remain at the lowest effective dose and should not exceed label directions because diphenhydramine overdose is associated with seizures and severe toxicity. [3]
Other sedating agents (including alcohol and other CNS depressants) should be avoided during diphenhydramine use because additive CNS effects increase the likelihood of harm. [3]
When Urgent Care or Poison Control Should Be Used
Emergency evaluation is indicated for suspected diphenhydramine overdose or concerning neurologic symptoms such as seizures, inability to stay awake, hallucinations, or severe confusion. [3]
Poison Control contact should be used for suspected overdose or uncertainty about dosing. [3]
Key Medication-Review Questions
A prescriber or pharmacist should review whether any seizure-risk factors exist, including seizure history, eating disorders, abrupt withdrawal from alcohol/benzodiazepines/barbiturates, severe head injury, or interacting medications that lower seizure threshold. [2]
Alternatives for Allergy/Itching or Sleep
If diphenhydramine is needed for allergy symptoms, non-sedating antihistamines are often preferred for reduced anticholinergic and sedation risk, pending a medication-specific review for safety with bupropion. [3]
If diphenhydramine is being used for sleep, non-diphenhydramine sleep-directed strategies should be considered to reduce anticholinergic burden and overdose risk. [3]