Can allergy medicine affect sex drive? Antihistamines and sexual side effects: During allergy season, you may find yourself reaching for Benadryl (diphenhydramine), Chlor-Trimeton (chlorpheniramine) or another over-the-counter antihistamine. allergy medicine Be warned: They can cause temporary erectile dysfunction and a lower libido. Winter is a time to think about the best natural treatments for allergies, …