What to Know About Antiemetics for Nausea

Medically Reviewed by Poonam Sachdev on November 02, 2021
3 min read

Antiemetics are a type of medication that can help you feel better when you're nauseated (you feel like throwing up). There are both over-the-counter (OTC) and prescription antiemetics. 

If you have mild nausea or vomiting, you can get an OTC antiemetic from your local drug store or grocery store. However, if you have severe nausea and are at risk of dehydration, your doctor may prescribe you a stronger anti-nausea medication.

There are two types of over-the-counter antiemetics:

Bismuth subsalicylate (Kapectate, Pepto-Bismol). This medication treats vomiting, nausea, and diarrhea. It is best for nausea brought on by the stomach flu or food poisoning. It works by reducing inflammation, slowing down the flow of fluids to the intestines, and potentially killing bacteria that may cause stomach upset.

It is normal to get a black tongue or see a darkening of your bowel movements when on this nausea-relief medicine. However, if you hear a ringing in your ears, call your doctor immediately, as that can be a sign of a serious side effect.

People who are allergic to salicylate medicines like aspirin should not take this medication. Additionally, bismuth subsalicylate is not appropriate for children under age 12. 

If your child is nauseated and has chickenpox or the flu, do not give them this medication, as it puts them at a higher risk for Reye's Syndrome, a swelling of the liver and brain.

Check with your doctor to make sure there will be no potentially harmful drug interactions, especially if you take blood thinners or prescriptions for arthritis, gout, or diabetes.

Antihistamines. Even though we think of antihistamines as allergy medications, some of them, like dimenhydrinate (Dramamine), can reduce nausea if it is caused by motion sickness or vertigo. These over-the-counter antiemetics work by making the inner ear less sensitive to motion and slowing or blocking the messages your brain sends that make you feel nausea. 

Antihistamines often make you tired, so don’t take them if you have to drive or do a task that requires your full attention.

Ask your doctor before taking antihistamines with sleeping medications, cold medicines, opioid pain relievers, muscle relaxers, or even alcohol.

Prescription antiemetic drugs are grouped by how they work in the body. Some groups of prescription anti-nausea drugs work better for certain conditions. Some medications combine two types of these medications to effectively treat different causes of nausea at one time.

Serotonin antagonists. Sometimes, the neurotransmitter serotonin can cause nausea. When something toxic enters your body, your body produces more serotonin to help expel the harmful substance quickly. This can cause nausea and other forms of gastric distress. Serotonin antagonists block serotonin's effects on the body. It is often prescribed for cancer patients going through chemotherapy, which may cause nausea.

Examples of commonly prescribed serotonin antagonists include:

  • Ondansetron (Zofran)
  • Granisetron (Sustol, Sancuso)
  • Dolasetron (Anzemet)
  • Palonosetron (Aloxi)

Neurokinin (NK-1) receptor antagonists. These medications help to suppress the vomiting reflex. These types of drugs help with delayed nausea that comes a few days after receiving a chemotherapy treatment. They are sometimes prescribed with another antiemetic to address immediate nausea.

Examples of NK-1 receptor antagonists include:

  • Aprepitant
  • Rolapitant
  • Fosaprepitant 

Dopamine antagonists. The neurotransmitter dopamine can also contribute to nausea when it binds with receptors in certain areas of the brain. Dopamine antagonists prevent this from happening.

Examples of dopamine antagonists include:

  • Prochlorperazine (Compro)
  • Metoclopramide (Reglan)

Benzodiazapines. These are usually prescribed as anti-anxiety drugs but can sometimes help with nausea if it is caused by anxiety and stress. 

Examples of benzodiazepines that can help with nausea include:

  • Lorazepam (Ativan)
  • Alprazolam (Xanax)

Cannabinoids. Cannabinoids are one of the chemical compounds found in marijuana. However, prescription cannabinoid medications do not get you "high." They are synthetic versions of these chemicals that can reduce nausea and stimulate your appetite. This makes them particularly useful for people experiencing nausea for long periods of time, like people with cancer. However, doctors usually only prescribe them when other anti-nausea treatments fail.

Examples of cannabinoid medications include:

  • Dronabinol
  • Nabilone

Follow directions on the medicine’s package and any directions given to you by your doctor. Some people think that taking more will make the medicine work better or faster; however, taking more than recommended can be harmful. 

Also, you should not use more than one anti-nausea medication at a time, unless directed by your doctor. If two different medications have the same active ingredients, you could end up taking too much.