Benadryl is an over-the-counter medicine that can be given to dogs. Diphenhydramine, the most common active ingredient, is an H 1 antagonist, which means it helps to prevent the uptake of histamine (a type of substance responsible for allergic reactions) by receptors in the body. An H 3-antihistamine is a classification of drugs used to inhibit the action of histamine at the H 3 receptor. H 3 receptors are primarily found in the brain and are inhibitory autoreceptors located on histaminergic nerve terminals, which modulate the release of histamine. Pseudoephedrine is used to treat nasal and sinus congestion, or congestion of the tubes that drain fluid from your inner ears. Includes pseudoephedrine side effects, interactions and indications. Learn about nasal allergy medications (nasal sprays) includes antihistamines, decongestants, and nasal steroid sprays, and their side effects. Claritin-D (loratadine / pseudoephedrine) relieves allergies and congestion without causing daytime sleepiness but it can keep you up at night. Zyrtec D (Cetirizine / Pseudoephedrine) relieves allergies and congestion without causing daytime sleepiness. It can keep you up at night if you take it too close to bedtime. Pseudoephedrine is a drug found in numerous prescription and behind-the-counter medications, including Sudafed Congestion (but not Sudafed PE), Zyrtec-D, and Claritin-D. When the sinus openings are inflamed, the blockage can cause infection. In these cases, antibiotics can be effective, but it might take more than one course of treatment. The Beers between use of drugs on the Beers list and ]-. What is the best medicine for runny nose? Almost everyone experiences this annoying problem, and whether you are a child in school or a businessman at work, you will find it difficult to go through the day with this burden and may want to get the answer for this question eagerly. Summary. Most individuals do not experience Claritin side effects when they take the medication as directed. While it is a safe medication that is sold over the counter, patients should be aware of all of the possible side effects they may experience during treatment, including dry mouth, drowsiness, jaundice or seizures.