Exercise has been shown in studies to improve sleep, but over-the-counter sedatives and antihistamines haven’t proven a “risk-benefit superiority” over placebo, researchers have reported.

Source: https://nationalpost.com/health/trouble-sleeping-youre-not-alone-how-to-beat-insomnia

In addition to these substances, delta-9 may also interact with certain medications such as calcium channel blockers, CNS depressants, antihistamines, and warfarin (Coumadin).

Source: https://www.chartattack.com/effective-way-to-take-delta-9/

In March, the FDA approved the first drug-eluting contact lenses, which release a payload of antihistamines over several hours to prevent or reduce itchy eyes.

Source: https://gizmodo.com/5-real-medical-treatments-that-sound-like-sci-fi-1848738466

Oral antihistamines, on the other hand, can be taken on an as-needed basis.

Source: https://tbrnewsmedia.com/medical-compass-welcome-to-hay-fever-season/

Some antihistamines can cause drowsiness and stomach/intestinal upsets.

Source: https://guyanatimesgy.com/misuse-of-pet-medication-final-consideration/