How Do Antiemetic Agents Work?

Antiemetic agents are a class of medications used to treat nausea and vomiting. These two symptoms are very common and are caused by different medical conditions, therapies, procedures, and medications. Although vomiting is considered to be a protective reflex action of the body to expel toxic substances in the stomach and gut, antiemetic medications are often necessary to suppress vomiting, especially to prevent dehydration.

Antiemetic agents are administered via oral and intravenous routes.

Types of antiemetic agents:

• Antihistamines: help prevent nausea and vomiting caused by motion sickness
• Antiemetic for stomach flu: relieves the symptoms of gastroenteritis
• Antiemetic during pregnancy: relieves morning sickness
• Antiemetic after surgery: prevents after-effects of anesthesia
• Antiemetic for cancer and chemotherapy: prevents side effects of chemotherapy and improves the quality of life

Antiemetic agents should be appropriately prescribed by a healthcare professional, considering the person in need of it, the underlying cause, the severity of the case, and the possible side effects. 

Antiemetic agents work in the following ways:

• Vomiting is controlled by the vomiting center in the brain, which is activated by triggers such as strong smell, thoughts and motion.
• Antiemetic agents bind to the receptors in the vomiting center of the brain stem and block their signaling pathways (that lead to nausea and vomiting), thus reducing the nausea sensation.
• The emetic response is mediated through multiple neurotransmitters (chemical messengers) including histamine, dopamine, serotonin, acetylcholine, and neurokinin.
• Neurotransmitters are the cells that receive the signals to send a nerve impulse.
• Antiemetic agents block the action of these neurotransmitters, which prevents the signals of nausea to reach the brain that helps to control nausea and vomiting.
• They inhibit the stimulation of the gastrointestinal tract, diaphragm, and abdominal muscles.
• In addition, they produce a calming effect on the brain that leads to slight drowsiness.

Apart from vomiting, antiemetic agents are also used in conditions such as:

• Chemotherapy-induced nausea and vomiting
• Motion sickness
• Postoperative nausea and vomiting
• Nausea and vomiting of pregnancy
• Side effects of opioid analgesics
• Gastroenteritis (infection and inflammation of the digestive system)
• Food poisoning
• Parkinsonism (condition that causes a combination of the movement abnormalities seen in Parkinson's disease)
• Cough
• Insomnia (trouble falling and/or staying asleep)
• Vertigo (a sensation of feeling off balance)
• Allergic reactions such as rash, itching, and runny nose
• Meniere's disease (disorder of the inner ear that can lead to dizzy spells and hearing loss)
• Anorexia (an eating disorder characterized by markedly reduced appetite or total aversion to food)

Common side effects include:

• Headache
• Constipation
• Fatigue
• Drowsiness
• Dizziness (feeling faint, weak, or unsteady)
• Dry mouth
• Loss of appetite

Other rare side effects include:

• Blurred vision
• Slow heartbeat
• Confusion
• Unusual weakness
• Hallucinations (involve hearing, seeing, feeling, smelling, or even tasting things that are not real)
• Hypertension/hypotension
• Urinary retention

Information contained herein is not intended to cover all possible side effects, precautions, warnings, drug interactions, allergic reactions, or adverse effects. Check with your doctor or pharmacist to make sure these drugs do not cause any harm when you take them along with other medicines. Never stop taking your medication and never change your dose or frequency without consulting your doctor.

Drug names include:                              

• Akynzeo
• Alka-Seltzer Plus Allergy
• Amisulpride
• Antivert
• Aprepitant
• Barhemsys
• Benadryl
• Benadryl Allergy Dye-Free LiquiGels
• Bonine
• Bonjesta
• Cesamet
• Children's Benadryl Allergy
• Children's Emetrol
• Children's Triaminic Thin Strips Allergy
• Cinvanti
• Compazine
• Compazine Spansules
• Diclegis
• Dimenhydrinate
• Diphenhydramine
• Doxylamine/pyridoxine
• Dramamine
• Dramamine Less Drowsy Formula
• Dronabinol
• Droperidol
• Emend
• Emetrol
• Fosaprepitant
• Fosnetupitant
• Hydroxyzine
• Inapsine
• Maldemar
• Marinol
• Meclizine
• Meclozine
• Meni D
• Metoclopramide
• Metozolv ODT
• Nabilone
• Nauzene
• Netupitant/palonosetron
• Nytol
• PediaCare Children's Allergy
• Phenadoz
• Phenergan
• Phosphorated carbohydrate
• Phosphoric acid/dextrose/fructose
• Prochlorperazine
• Prochlorperazine edisylate
• Prochlorperazine mesylate
• Promethazine
• QlearQuil Nighttime Allergy Relief
• Reglan
• Rolapitant
• Scopace
• Scopolamine
• Simply Sleep
• Sodium citrate/dextrose/fructose
• Sominex
• Syndros
• Tigan
• Tranquil Nighttime Sleep Aid
• Transderm Scop
• Trimethobenzamide
• Unisom SleepGels
• Unisom SleepMelts
• Varubi
• VertiCalm
• Vistaril
• ZzzQuil