Anti-Nausea Medicine: What Products Should I Use?

Nausea is an uncomfortable or “queasy” feeling with or without the urge to vomit. How to treat nausea can be determined by its cause. Both over-the-counter (OTC) and prescription medications are available to help prevent or relieve queasiness.

This article will discuss available medicines for nausea on the market and how to choose the right one for you.

What Causes Nausea?

Nausea is an uncomfortable or “queasy” feeling with or without the urge to vomit. There are many causes of nausea. A person can experience nausea due to many different signals sent to the brain and throughout the body, and knowing the cause can help decide the best treatment. 

Potential causes of nausea may include, but are not limited to:

• Motion sickness: Motion sickness occurs when your body gets confused by mixed signals from your eyes, ears, and body. It often occurs during travel in cars, planes, boats, or amusement park rides.
• Pregnancy: Nausea or morning sickness is a common symptom early in pregnancy. While the cause of morning sickness is still unknown, it may be due to changes in hormones, blood pressure, or metabolism. It may also be due to the physical changes that happen during pregnancy.  
• Viral infection: Gastroenteritis or the stomach flu is a virus that attacks the intestines. In this case, nausea lets your body know that something is not right. 
• Medications: Several medications may cause nausea as a side effect. Two common drug groups that cause nausea are chemotherapy and general anesthesia. A healthcare provider may administer preventative anti-nausea medications for postoperative nausea and vomiting (PONV) or chemotherapy-induced nausea and vomiting (CINV). 
• Gastrointestinal disorders: Peptic ulcer disease and gastroparesis can also cause nausea.
  

Common Anti-Nausea Medications for Adults

OTC and prescription medications are available for the treatment and prevention of nausea.

OTC Medications 

Antihistamines help you feel better by blocking histamine and the "vomiting center" (also called the chemoreceptor trigger zone) in the brain. It also decreases electrical signals sent to the ear.

There are several OTC antihistamines available, including:

• Dramamine (dimenhydrinate)
• Dramamine Less Drowsy or Bonine (meclizine)
• Benadryl (diphenhydramine)

While certain antihistamines can be effective in preventing motion sickness, newer antihistamine agents, such as Zyrtec, have no effect on nausea.

Prescription Medications

Antihistamines

Phenergan (promethazine) is a prescription-only antihistamine that can prevent or control nausea related to anesthesia or surgery.

Anticholinergics

Transderm Scop (scopolamine) is an anticholinergic medicine that prevents nausea and vomiting. It is a removable patch that is applied to the skin.

Anticholinergics work by blocking the transmission of acetylcholine. Acetylcholine is a chemical messenger (neurotransmitter) that attaches to the surface and activates the vomiting center in the body.

Anticholinergics like scopolamine are effective for:

• Motion sickness
• Prevention of nausea caused by general anesthesia from a surgical procedure

Dopamine Antagonists

Dopamine antagonists work by blocking dopamine in the vomiting center in the brain, They also block serotonin at high doses.

Reglan (metoclopramide) is a dopamine antagonist that treats nausea and vomiting due to gastroesophageal reflux disease (GERD) or diabetic gastroparesis. It can also help manage CINV.

Dopamine receptor antagonists are effective for: 

• Prevention of chemotherapy-related nausea or vomiting
• Prevention and treatment of nausea caused by general anesthesia from a surgical procedure
• Gastroparesis

Selective Serotonin Receptor (5-HT3) Antagonists

5-HT3 antagonists work by blocking serotonin in the vagal nerve and in the vomiting center in the brain.

Medications available include: 

• Ondansetron
• Sancuso (granisetron)
• Palonosetron

5-HT3 antagonists are effective for: 

• Prevention of chemotherapy-related nausea or vomiting
• Prevention and treatment of nausea caused by general anesthesia from a surgical procedure

Other Anti-Nausea Agents

Other agents used for nausea are corticosteroids such as dexamethasone and methylprednisolone, antipsychotic medications like olanzapine and prochlorperazine, and Emend (aprepitant).

Anti-Nausea Medications for Kids

Anti-nausea medications have a place in treatment for children, but it is best to speak to a healthcare provider before starting. Anti-nausea drugs have different age cut-offs, doses, and side effects, so it's critical that the medication is appropriate and safe for the child's specific age and health condition.

Motion Sickness

Anti-nausea medications and the recommended age cut-offs (see package label or speak to your healthcare provider or pharmacist for actual doses):

• Dramamine for Kids: Used for kids 2 years and older
• Benadryl: Used for kids 6 and older
• Dramamine Less Drowsy: Used for kids 12 and older
• Phenergan and scopolamine (prescription only)
  

Post-Operative Nausea and Vomiting (PONV)

Commonly prescribed medications for the prevention of PONV are:

• Ondansetron
• Dexamethasone
• Metoclopramide

These medications can also be used for nausea associated with chemotherapy.

Anti-Nausea Medication in Pregnancy

Nausea during pregnancy, or morning sickness, is treated using different techniques to reduce the symptoms and to make pregnancy more comfortable. Morning sickness is different in every person. 

Mild to Moderate Morning Sickness

You can try the following methods to help relieve motion sickness symptoms:

• Lifestyle and diet changes: Eating bland foods and drinking plenty of water. Get enough rest and avoid exhaustion.
• Acupressure and acupuncture: Applying pressure to specific points on the body (acupressure) or receiving acupuncture treatment may help some pregnant people.
• Avoid triggers: Triggers can vary from person to person. Know those triggers, and avoid smells or situations that trigger nausea.
• Vitamin B6 supplements: Studies suggest vitamin B6 may reduce nausea during pregnancy.

Severe or Chronic Morning Sickness

In severe cases of morning sickness, see your healthcare provider for medications safe in pregnancy. Commonly prescribed medications include:

• Dimenhydrinate
• Promethazine
• Doxylamine/pyridoxine
• Ondansetron
  

Always talk to your healthcare provider before starting a new treatment during pregnancy.

Which Anti-Nausea Medications Are the Most Effective?

Every person has a threshold for nausea that can change frequently. The threshold can differ from person to person, making some people more likely to experience nausea than others.

The three major ways nausea occurs are through electrical signals sent to the ear (also called vestibular stimulation), signals sent from internal organs (also called visceral stimuli), and signals to the “vomiting center” in the brain (also called the chemoreceptor trigger zone).

Each of these mechanisms is associated with chemical messengers (neurotransmitters). Knowing these helps your healthcare provider pick the best medicine for use.

• Vestibular stimulation: Histamine and acetylcholine
• Visceral stimuli: Dopamine and serotonin
• Chemoreceptor trigger: Dopamine, serotonin, and substance p (also called neurokinin-1)

Motion sickness is associated with an increase in histamine and acetylcholine. Therefore, common medications used for motion sickness are antihistamines and anticholinergics.

On the other hand, gastroenteritis and PONV are associated with more dopamine and serotonin. Common medications for gastroenteritis and PONV are dopamine receptor antagonists and selective serotonin antagonists.

Motion Sickness

Anticholinergics and antihistamines are equally effective at preventing nausea related to motion sickness.

Gastroenteritis

A review of several studies showed that ondansetron is most effective compared with other anti-nausea agents for reducing vomiting associated with gastroenteritis. It is important to drink plenty of fluids to avoid dehydration.

Post-Operative Nausea and Vomiting

First-line treatments for PONV are usually ondansetron or dexamethasone. Both are equally effective.

Ondansetron is used often because of its low cost and mild side effects. However, it may lengthen the QT interval and should be used with caution in some people.

Dexamethasone has the added benefit of pain control along with its anti-nausea effects. 

Chemotherapy-induced Nausea and Vomiting (CINV)

Treatment is tailored for each individual by how likely a chemotherapy agent is to cause nausea and vomiting. The provider may change the medications based on the individual's response.

• If the chemotherapy has a more than 90% likelihood of causing nausea and vomiting (high risk): Emend (aprepitant), ondansetron, dexamethasone, and Zyprexa (olanzapine) are used in combination. 
• If the chemotherapy has a 30% to 90% likelihood of causing nausea and vomiting (moderate risk): Aprepitant, ondansetron, and dexamethasone may be used in combination.
• If the chemotherapy has a less than 30% likelihood of causing nausea and vomiting (low risk): Ondansetron may be used alone in some cases.
  

When to See a Healthcare Provider

In mild cases, nausea should resolve on its own. The use of OTC medications can help prevent or treat nausea related to certain triggers, like motion sickness. In other cases, such as for nausea related to a medication or illness, you may need to get a prescription from a healthcare provider for the right treatment.

Call your healthcare provider if you are pregnant and have severe nausea and vomiting or persistent vomiting with significant weight loss. You may be experiencing a more severe form of nausea and vomiting known as hyperemesis gravidarum.

Summary

Nausea is a common and uncomfortable feeling. However, there are several OTC and prescription products available that are effective at preventing or treating nausea, depending on its cause.

If you know what's causing your nausea, ask your pharmacist or healthcare provider about which medicine will be most appropriate for you. You can also read the product labels for available OTC medicines to understand their uses better.

You should consult your provider if you're experiencing nausea with no known cause, as they can help you get to the root of what's causing it.

The author would like to recognize and thank Norma Ponce, PharmD, MHA for contributing to this article.