Unwanted side effects of sedating antihistamines
Older adults are especially sensitive to the central nervous system- and anticholinergic-related side effects of sedating antihistamines because of decreased cholinergic neurons or receptors in the brain, reduced hepatic and renal function, and increased blood-brain permeability.
These patients also often have coexisting conditions and often take multiple medications that increase the risk of drug-drug interactions and the potential for sedative adverse effects.
You will find a full list of side-effects in the manufacturer's information leaflet supplied with your medicine but the table below contains the most common ones. Never give it to other people even if their condition appears to be the same as yours. Take them to your local pharmacy which will dispose of them for you.
These antihistamines are more selective on peripheral H1 receptors and have a lower affinity for cholinergic and alpha-adrenergic receptor sites, which reduces the risk of anticholinergic and central nervous system side effects.H3 receptor antagonists could provide new treatment options for sleep disorders, weight loss, neuropathic pain, obesity, movement disorders, schizophrenia, attention deficit disorders, and Alzheimer’s dementia, while the development of antagonists for H4 receptors may lead to new treatment options for autoimmune inflammatory diseases.1,2 The first H1 sedating antihistamines have been available for more than 60 years and were synthesized based on a chemical structure similar to that used to develop cholinergic muscarinic antagonists, tranquilizers, and antihypertensive agents.These antihistamines have low receptor specificity and interact with both peripheral and central histamine receptors and readily cross the blood-brain barrier.Other sleep aids often contain the antihistamine doxylamine (eg, Unisom).H2 blockers (eg, ranitidine, famotidine) commonly are used for the treatment of heartburn and gastroesophageal reflux disease.