The dehydrating effects of antihistamines are what make them effective at combating allergy symptoms like a runny nose. While this may be great for a bout of sniffles, this same mechanism can work against us in the bedroom. “Antihistamines can lead to narrowing of blood vessels to constrict, so there’s less blood flow and therefore fewer secretions throughout the body,” OB-GYN Dr. Alyssa Dweck told Health. As a result, taking an antihistamine before sex may make self-lubrication difficult for people with vaginas. Additionally, these medications can also dehydrate the mucus membrane of the mouth (via Self). Unfortunately, nothing interrupts a makeout session quite like an unpleasant case of dry mouth.
Some antihistamines can also make us sleepy if they contain diphenhydramine (Benadryl), which may make us more inclined to retire to the bedroom — but not for sex. Even newer antihistamine drugs made with different active ingredients aren’t immune to this potential side effect. Board-certified allergist Dr. Charles Joseph Lane told Self that this sedative effect is often reported by his patients in connection with Zyrtec. Alternatively, some antihistamines like Benadryl or Chlor-Trimeton may lower one’s sex drive (via TIME).