• Clinical science



Antiemetics are a heterogeneous group of drugs used to treat various causes of nausea and vomiting. Different antiemetics act on different receptors, and they may have a peripheral effect, a central effect, or both. Whereas serotonin antagonists, for example, bind 5-HT3 receptors and effectively combat cytotoxic drug nausea, certain anticholinergic drugs target M1 receptors and specifically treat motion sickness (kinetosis). Hospitals and clinics commonly use the dopamine D2 antagonist metoclopramide. However, because of its strong central effect and possible extrapyramidal side effects, metoclopramide must be used with caution.


Group Drug Antagonized receptor Mechanism Specific features Side effects
Dopamine receptor antagonists/ prokinetic agents




Serotonin receptor antagonists Ondansetron (Zofran®) 5-HT3
  • Central-acting antiemetic effect
  • Peripheral inhibition of the intestinal tract's vagal nerve signals
  • Especially effective against chemotherapy and radiation-induced vomiting and postoperative nausea and vomiting (PONV)
Anticholinergic agents Scopolamine M1
  • Especially effective against motion sickness or vestibular-induced nausea and vomiting
Antihistamines Meclizine, dimenhydrinate, diphenhydramine,doxylamine, promethazine H1
  • Antiemetic effect in the CNS






We list the most important contraindications. The selection is not exhaustive.

  • 1. Le T, Bhushan V, Chen V, King M. First Aid for the USMLE Step 2 CK. McGraw-Hill Education; 2015.
  • 2. Le T, Bhushan V. First Aid for the USMLE Step 1 2015. McGraw-Hill Education; 2014.
  • 3. drugbank.ca. Prochlorperazine. https://www.drugbank.ca/drugs/DB00433. Updated December 8, 2016. Accessed February 21, 2017.
  • 4. U.S. Food and Drug Administration. FDA Requires Boxed Warning and Risk Mitigation Strategy for Metoclopramide-Containing Drugs Agency warns against chronic use of these products to treat gastrointestinal disorders. https://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/2009/ucm149533.htm. Updated April 18, 2013. Accessed February 21, 2017.
  • 5. Drugs.com. Ondansetron. https://www.drugs.com/pro/ondansetron.html. Updated February 21, 2017. Accessed February 21, 2017.
  • 6. UpToDate. Prochlorperazine: Drug information. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/prochlorperazine-drug-information. Last updated January 1, 2017. Accessed March 22, 2017.
  • 7. UpToDate. Metoclopramide: Drug information. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/metoclopramide-drug-information. Last updated January 1, 2017. Accessed March 22, 2017.
  • 8. McInnis M, Mehta S, Lewis C, et al. Step-Up to USMLE Step 1 2015 . Lippincott Williams & Wilkins; 2014.
  • 9. Pedigo NW Jr, Brizzee KR. Muscarinic cholinergic receptors in area postrema and brainstem areas regulating emesis. Brain Res Bull. 1985; 14(2): pp. 169–77. pmid: 3995361.
  • 10. Katzung B,Trevor A. Basic and Clinical Pharmacology. McGraw-Hill Education; 2014.
last updated 11/06/2019
{{uncollapseSections(['gEbFEv', 'hEbcvv', 'iEbJvv', 'QEbuvv'])}}