What are the side effects of antihistamines?

Table of Contents

Drowsiness.
Dry mouth, dry eyes.
Blurred or double vision.
Dizziness and headache.
Low blood pressure.
Mucous thickening in the airways.
Rapid heart rate.
Difficulty urinating and constipation.

What causes the side effects of H1 receptor antihistamines?

First-generation H1 antihistamines cross the blood-brain barrier, and in usual doses, they potentially cause sedation and impair cognitive function and psychomotor performance. These medications, some of which have been in use for more than 6 decades, have never been optimally investigated.

What is the mechanism of antihistamine?

The primary mechanism of antihistamine action in the treatment of allergic diseases is believed to be competitive antagonism of histamine binding to cellular receptors (specifically, the H1-receptors), which are present on nerve endings, smooth muscles, and glandular cells.

Are antihistamines anticholinergic?

Anticholinergic drugs include some antihistamines, tricyclic antidepressants, medications to control overactive bladder, and drugs to relieve the symptoms of Parkinson’s disease.

What is the safest antihistamine?

Loratadine, cetrizine, and fexofenadine all have excellent safety records. Their cardiovascular safety has been demonstrated in drug-interaction studies, elevated-dose studies, and clinical trials. These three antihistamines have also been shown safe in special populations, including pediatric and elderly patients.

Can antihistamines affect your heart?

Antihistamines, which are commonly used to treat symptoms such as a runny nose or sneezing, are generally safe for patients with abnormal heart conditions. However, the FDA has warned that antihistamines taken in conjunction with some high blood pressure medications may cause a spike in blood pressure.

Are H2 blockers anticholinergic?

H2 blockers are reversible competitive blockers of histamine at H2 receptors, particularly those in the gastric parietal cells (where they inhibit acid secretion). The H2 antagonists are highly selective, they do not affect the H1 receptors, and they are not anticholinergic agents.

Which of the following is the most frequent side effect of H1-antihistamines that is less common with second gen antihistamines?

The most common adverse effects noted for second-generation agents include drowsiness, fatigue, headache, nausea and dry mouth.

Is antihistamine a vasoconstrictor?

Moreover, they found that antihistamines potentiated the effect of catecholamine vasoconstrictor activity [13]. Histamine receptors are found throughout the cerebral vasculature and play a role in regulating vascular tone [14].

What do histamine 2 receptors do?

The histamine receptor H2 belongs to the rhodopsin-like family of G protein-coupled receptors. It is an integral membrane protein and stimulates gastric acid secretion. It also regulates gastrointestinal motility and intestinal secretion and is thought to be involved in regulating cell growth and differentiation.

Which drugs are anticholinergic?

Anticholinergics are drugs that block the action of acetylcholine ….Examples of these drugs include:

atropine (Atropen)
belladonna alkaloids.
benztropine mesylate (Cogentin)
clidinium.
cyclopentolate (Cyclogyl)
darifenacin (Enablex)
dicylomine.
fesoterodine (Toviaz)

Is cetirizine an anticholinergic?

It is well tolerated by elderly patients. Cetirizine has a low rate of penetration of the blood-brain barrier, and it has minimal central nervous system impairment. Furthermore, it can be given once a day. Cetirizine’s low incidence of sedation and anticholinergic side effects contribute to its high profile of safety.