Examples include: receptors are primarily found in the brain and are inhibitory autoreceptors located on histaminergic nerve terminals, which modulate the release of histamine.Histamine release in the brain triggers secondary release of excitatory neurotransmitters such as glutamate and acetylcholine via stimulation of H Research into these drugs led to the discovery that they were H1 antagonists and also to the development of H2 antagonists, where H1 antihistamines affected the nose and the H2 antihistamines affected the stomach.Newer non-sedating antihistamines are generally thought to be somewhat less effective.Antihistamine side effects that very occasionally occur include urine retention in males and fast heart rate.
At higher doses, they can also cause sodium channel blockade with subsequent cardiovascular effects including QT prolongations and Torsades de Pointes.Different studies have reported on antihistamine use in children, with various studies finding evidence that certain antihistamines could be used by children 2 years of age, and other drugs being safer for younger or older children.Antihistamines are a group of medicines which act by blocking the action of the chemical called histamine in the body.If you are one of the many people who get hay fever each year, you will know all about antihistamines. Some of these medicines are available to buy over the counter from your pharmacist. These medicines come in a variety of forms, as mentioned above.This is one of the most common uses of antihistamines. Your doctor or pharmacist will advise you on how to take your medication, including what dose and how often.