The drug is an ingredient in several products sold as sleep aids, either alone or in combination with other ingredients such as acetaminophen (paracetamol). Diphenhydramine can cause minor psychological dependence. Topical diphenhydramine is sometimes used especially for people in hospice.This use is without indication and topical diphenhydramine should not be used as treatment for nausea because research does not indicate this therapy is more effective than alternatives. This activity is responsible for the side effects of dry mouth and throat, increased heart rate, pupil dilation, urinary retention, constipation, and, at high doses, hallucinations or delirium.Long term anticholinergic use is associated with an increased risk for cognitive decline and dementia among older people.
Thus, upregulation of allopregnanolone biosynthesis in corticolimbic neurons may offer a novel non-traditional pharmacological target for a new generation of potent non-sedating, anxiolytic medications for the treatment of anxiety, depression, and PTSD: selective brain steroidogenic stimulants (SBSSs).These are used to relieve itching, and have the advantage of causing fewer systemic effects (e.g., drowsiness) than oral forms.Because of its sedative properties, diphenhydramine is widely used in nonprescription sleep aids for insomnia.Diphenhydramine can be quantified in blood, plasma, or serum.This discovery led to a search for viable antidepressants with similar structures and fewer side effects, culminating in the invention of fluoxetine (Prozac), a selective serotonin reuptake inhibitor (SSRI). FDA has required special labeling warning against use of multiple products that contain diphenhydramine.