Treatment with Benicar was well tolerated, with an incidence of adverse reactions similar to placebo. Events generally were mild, transient and had no relationship to the dose of Benicar. The overall frequency of adverse reactions was not dose-related.
Sometimes you may also get an itchy rash on your skin, called hives. Antihistamines reduce or block histamines, so they stop allergy symptoms. Antihistamines work well to relieve symptoms of different types of allergies, including seasonal (hay fever), indoor, and food allergies, but they can't relieve every symptom. To treat nasal congestion, your doctor may recommend taking a decongestant.
1 They work by preventing histamines from attaching to certain sites on cells and causing allergic reactions and allergy symptoms. 2  Some over-the-counter antihistamines and some prescription antihistamines can cause drowsiness. 3  Be sure you know when it's safe to use them. 4  Don't drink alcohol while taking antihistamines.ome can cause drowsiness or sedation, however. There are newer antihistamines available that don't cause as much drowsiness. These include the the prescription drug Allegra (fexofenadine), and Zyrtec (cetirizine) and Claritin (loratadine), which are now available without a prescription. Sedating Antihistamines.