<unk> s are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take<unk> s as an inexpensive, not patented (generic), drug that can be bought without a prescription and relieves from nasal congestion, sneezing, or hives caused by pollen, dust mites, or animal allergy with few side effects.<unk> s are usually for short-term treatment. Chronic allergies increase the risk of health problems which<unk> s might not treat, including asthma, sinusitis, and lower respiratory tract infection. Consultation of a medical professional is recommended for those who intend to take<unk> s for longer-term use. Although people typically use the word<unk> ” to describe drugs for treating allergies, doctors and scientists use the term to describe a class of drug that opposes the activity of histamine receptors in the body. In this sense of the word,<unk> s are subclassified according to the histamine receptor that they act upon. The two largest classes of<unk> s are H1-antihistamines and H2-antihistamines. H1-antihistamines work by binding to histamine H1 receptors in mast cells, smooth muscle, and endothelium in the body as well as in the tuberomammillary nucleus in the brain.<unk> s that target the histamine H1-receptor are used to treat allergic reactions in the nose (e.g., itching, runny nose, and sneezing). In addition, they may be used to treat insomnia, motion sickness, or vertigo caused by problems with the inner ear. H2-antihistamines bind to histamine H2 receptors in the upper gastrointestinal tract, primarily in the stomach.<unk> s that target the histamine H2-receptor are used to treat gastric acid conditions (e.g., peptic ulcers and acid reflux). Histamine receptors exhibit constitutive activity, so<unk> s can function as either a neutral receptor antagonist or an inverse agonist at histamine receptors. Only a few currently marketed H1-antihistamines are known to function as inverse agonists.
Antihistamine
Antileukotriene
Aeroallergen
Depressogen
Anticorticosteroid
Allergen
Opioid
Querulant