Sedating antihistamines over the counter uk
Histamine-1 receptors are located in the airways, blood vessels and gastrointestinal tract (stomach and esophagus).
Histamine-1 receptors are also found in the brain and spinal cord.
Other types of allergy drugs include: Corticosteroids: These come as nasal sprays, topical creams and ointments, tablets, injectables and eye preparations. Mast cell stabilizers: These can help prevent allergic reactions from happening when taken regularly.
During an allergic reaction, mast cells release histamine and other substances.
Antihistamines are very good at relieving symptoms of an allergic reaction, such as: First-generation antihistamines were developed more than seventy years ago and are still in widespread use today.
They act on histamine receptors in the brain and spinal cord and in the rest of the body (called the periphery).
In addition to oral dosage forms, antihistamines come as creams, lotions, nasal sprays, and eye drops; the latter to relieve symptoms associated with allergic conjunctivitis.This causes white blood cells to release an antibody which then binds to what are known as mast cells.The mast cells rupture – and in the process, release biochemical substances including histamine.Most second-generation antihistamines do not cause drowsiness, although some (such as cetirizine and fexofenadine), may be more likely to do so at higher dosages.Allergies occur when the body's immune system responds to a substance it considers an "invader." Substances that provoke the immune system into an allergic response are known as allergens. What might trigger a life-threatening allergic response in one person might cause absolutely no harm in another.