What are some of the common side effects observed with antihistamines? March 31, 2020 01:00 Updated DizzinessDry mouthDrowsinessFeeling nervous, excited, or irritableChanges in vision, such as blurry visionDecreased appetite Related articles What are the two types of rhinitis? What over the counter medications are available? What is allergic rhinitis? Can I drink alcohol when I take antihistamines?