Phenergan tablets are used to treat a variety of allergic conditions, including allergic contact dermatitis, allergic reactions to drugs, hives (urticaria), and bites and stings, to relieve symptoms of redness, swelling and itching of the skin; also to relieve upper respiratory tract symptoms of allergic rhinitis, including nasal congestion, runny itchy nose and sneezing, caused by seasonal allergies like hayfever. Phenergan tablets are also used as an antiemetic to reduce nausea and vomiting due to several conditions including postoperative vomiting, irradiation sickness, drug-induced nausea and motion sickness. Phenergan tablets have sedative properties, which can be used to help with management of the symptoms of measles and chicken pox; also for short-term sedation. Histamine is a chemical released from mast cells, (cells involved in allergies) as part of the body’s defence mechanism during an allergic reaction and binds to H1 receptors in small blood vessels causing them to leak, allowing white blood cells and blood proteins into the tissues. These infiltrating cells produce inflammatory chemicals (prostaglandins and leukotrienes) that cause tissue swelling and irritation, which are symptoms of an allergic reaction. Promethazine in Phenergan is an H1 receptor antagonist and works by binding to histamine receptors and blocking the action of histamine without blocking its secretion. This action blocks histamine-mediated allergic reactions, relieving symptoms in the upper respiratory tract like nasal congestion, runny itchy nose and sneezing, and in the skin like redness, swelling and itching.
Promethazine hydrochloride, an antihistamine belonging to phenothiazine group of drugs that also has antiemetic (prevents nausea) and sedative properties. They also contain lactose, starch maize, povidone, magnesium stearate, hypromellose, macrogol 200, blue opaspray.
Side effects when taking Phenergan tablets include: dry mouth, gastro-intestinal disturbances (diarrhoea, constipation, nausea, vomiting or abdominal pain) loss of appetite, tiredness, sleepiness, restlessness, dizziness, blurred vision.
Individuals who are allergic to promethazine or any ingredients in Phenergan, are allergic to sulphites, benzoates or phenothiazines, are pregnant or are breastfeeding, have had jaundice induced by other phenothiazine derivatives, are taking medicines that interact with Phenergan, including: monoamine oxidase inhibitors (MAOIs) (up to 14 days previously), tricyclic antidepressants, sedatives and hypnotics, opioid analgesics, barbiturates should not take Phenergan.