What are antiemetic drugs?
Antiemetic drugs are prescribed to help with nausea and vomiting that are side effects of other drugs. This may include drugs for anesthesia used during surgeries or chemotherapy for cancer. Antiemetic drugs are also used for nausea and vomiting caused by:
- motion sickness
- morning sickness during pregnancy
- severe cases of the stomach flu (gastroenteritis)
- other infections
These drugs work by interfering with the neurotransmitter receptors involved in vomiting. Neurotransmitters are the cells that receive the signals to send a nerve impulse. The pathways that control these bodily reactions are complex. The type of antiemetic drug used will depend on the cause.
Types of antiemetic drugs
Some antiemetic drugs are taken by mouth. Others are available as an injection or as a patch placed on your body so you don’t have to swallow anything. The type of antiemetic drug you should take depends on what is causing your symptoms:
Antiemetics for motion sickness
Antihistamines that prevent nausea and vomiting caused by motion sickness are available over the counter (OTC). They work by keeping your inner ear from fully sensing motion and include:
Antiemetics for stomach flu
The stomach flu, or gastroenteritis, is caused by a virus or bacteria. The OTC drug bismuth-subsalicylate (Pepto-Bismol) works by coating your stomach lining. You can also try OTC glucose, fructose, or phosphoric acid (Emetrol).
Antiemetics for chemotherapy
Nausea and vomiting are a common part of chemotherapy treatment. Antiemetic drugs are used before and after chemotherapy to prevent symptoms.
Some prescription treatments include:
- serotonin 5-HT3 receptor antagonists: dolasetron (Anzemet), granisetron (Kytril, Sancuso), ondansetron (Zofran, Zuplenz), palonosetron (Aloxi)
- dopamine antagonists: prochlorperazine (Compazine), domperidone (Motilium, not available in the US), olanzapine (Zyprexa)
- NK1 receptor antagonists: aprepitant (Emend), rolapitant (Varubi)
- corticosteroids: dexamethasone (DexPak)
- cannabinoids: cannabis (medical marijuana), dronabinol (Marinol)
Antiemetics for surgery
Postoperative nausea and vomiting (PONV) can be caused by the anesthesia used during a surgery. Prescription drugs used for treating PONV include:
- serotonin 5-HT3 receptor antagonists: dolasetron, granisetron, ondansetron
- dopamine antagonists: metoclopramide (Reglan), droperidol (Inapsine), domperidone
- corticosteroids: dexamethasone
Antiemetics for morning sickness
Morning sickness is common during pregnancy. However, antiemetic drugs aren’t usually prescribed unless it’s severe.
Hyperemesis gravidarum is a pregnancy complication that causes severe nausea and vomiting. If you have this condition, your doctor may prescribe:
- antihistamines, such as dimenhydrinate
- vitamin B-6 (pyridoxine)
- dopamine antagonists, such as prochlorperazine, promethazine (Pentazine, Phenergan)
- metoclopramide if other treatments don’t work
Side effects of antiemetic drugs
The side effects depend on the type of antiemetic drug you take:
- bismuth-subsalicylate: dark-colored tongue, grayish-black stools
- antihistamines: drowsiness, dry mouth
- dopamine antagonists: dry mouth, fatigue, constipation, tinnitus, muscle spasms, restlessness
- neurokinin receptor agonists: decreased urination, dry mouth, heartburn
- serotonin 5-HT3 receptor antagonists: constipation, dry mouth, fatigue
- corticosteroids: indigestion, acne, increased appetite and thirst
- cannabinoids: changes in perception, dizziness
If you experience any of the following, consult your doctor:
- worsening of nausea or vomiting
- severe constipation
- muscle weakness
- loss of hearing
- rapid heartbeat
- severe drowsiness
- slurred speech
- psychological symptoms, like hallucinations or confusion
Natural antiemetic treatments
The most well-known natural antiemetic is ginger (Zingiber officinale). Ginger contains 5-HT3 antagonists known as gingerols. Clinical studies show that ginger may be effective in treating nausea and vomiting. Steep fresh ginger in hot water to make tea, or try candied ginger, ginger biscuits, or ginger ale.
Aromatherapy with peppermint essential oil may also be a safe and effective way to overcome nausea and vomiting. Try rubbing a couple drops into the back of your neck and taking deep breaths.
Cannabis has also been shown to be an effective antiemetic. It’s now available legally in many states, but may be considered an illegal drug in others.
Antiemetic drugs safe for pregnancy
Motion sickness drugs like meclizine and dimenhydrinate are safe for pregnant women. Vitamin B-6 and dopamine antagonists have been found to be safe, but are only used in severe cases of morning sickness.
Cannabis or marijuana is not safe to use during pregnancy. The drug is linked to lower birth weight and increased risk of brain and behavioral problems in children. Pepto-Bismol is also not recommended.
Antiemetic drugs safe for children
It’s always a good idea to consult a doctor before giving medication to children.
For motion sickness
Dimenhydrinate and diphenhydramine (Benadryl) can be used to treat nausea in children over 2 years old, but make sure you follow dosage instructions.
Recent studies have found that ondansetron may be safe and effective for children with a severe case of gastroenteritis.
Promethazine shouldn’t be used by babies or young children. Don’t give bismuth-subsalicylate to children 12 years of age or younger.
There are many antiemetic drugs for treating nausea and vomiting, but the drug you should try depends on what’s causing your symptoms. Make sure you read the labels carefully or follow your doctor’s instructions. For mild cases of nausea or vomiting, try an herbal therapy like ginger.