pro·​phy·​lax·​is | \ ˌprō-fə-ˈlak-səs also ˌprä- How to pronounce prophylaxis (audio) \
plural prophylaxes\ ˌprō-​fə-​ˈlak-​ˌsēz How to pronounce prophylaxes (audio) also  ˌprä-​ \

Definition of prophylaxis

: measures designed to preserve health (as of an individual or of society) and prevent the spread of disease

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Did You Know?

In Greek, phylax means "guard", so prophylactic measures guard against disease by taking action ahead of time. Thus, for example, before the polio vaccine became available, prophylaxis against polio included avoiding crowds and public swimming pools. These days a well-known kind of prophylactic is used to prevent sexually transmitted diseases; but prophylactic measures only work when people use them.

Examples of prophylaxis in a Sentence

Recent Examples on the Web

Rabies post-exposure prophylaxis is generally recommended for individuals who have a possible exposure to the virus. Tara C. Smith, SELF, "What Happens When You Get Rabies? An Epidemiologist Explains," 24 Jan. 2019 Depending on the situation at hand, your doctor may decide to administer what’s called a prophylaxis against Lyme disease, Luis Marcos, M.D., the fellowship program director at Stony Brook Medicine’s division of infectious diseases, tells SELF. Kate Sheridan, SELF, "Here’s Exactly What to Do if a Tick Bites You," 14 July 2018 Aureomycin spawned a class of antibiotics called the tetracyclines still used for everything from soft tissue infections to malaria prophylaxis. Aaron Gilbreath, Longreads, "We Are Scientists," 5 June 2018 Wash any wounds with soap and water to decrease the chance of infection, and see a doctor before considering the need for a rabies vaccination, known as postexposure prophylaxis. Brittany Britto,, "Explainer: On groundhogs, rabies and what we know (and don't know) about Carroll's rodents," 9 May 2018 The Food and Drug Administration administered guidelines that prohibit antibiotic use for growth promotion, but continue to allow the routine use of antibiotics on animals that aren’t sick for prophylaxis. Matthew Wellington, STAT, "Lawmakers must act on limiting antibiotic use in food animals," 19 Mar. 2018 That's why Planned Parenthood helped to spread awareness on National Black HIV/AIDS Awareness Day by releasing new educational videos explaining pre-exposure prophylaxis (PrEP) and post-exposure prophylaxis (PEP), two HIV prevention medications. Elly Belle, Teen Vogue, "Planned Parenthood Videos Explain HIV Prevention Drugs PrEP and PEP," 8 Feb. 2018 In Australia, for example, physicians must provide victims with prophylaxis and emergency contraception, and can offer medical exams without a police report. Andrea Sachs,, "Women who travel share a universal issue: Sexual harassment," 15 Dec. 2017 The only problem was that testing a prophylaxis would require them to introduce the diseases to previously unexposed human subjects. Sushma Subramanian, Slate Magazine, "Worse Than Tuskegee," 26 Feb. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'prophylaxis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of prophylaxis

1683, in the meaning defined above

History and Etymology for prophylaxis

New Latin, from Greek prophylaktikos

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Time Traveler for prophylaxis

The first known use of prophylaxis was in 1683

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More Definitions for prophylaxis


pro·​phy·​lax·​is | \ -ˈlak-səs How to pronounce prophylaxis (audio) \
plural prophylaxes\ -​ˈlak-​ˌsēz How to pronounce prophylaxes (audio) \

Medical Definition of prophylaxis

: measures designed to preserve health and prevent the spread of disease : protective or preventive treatment prophylaxis against viral diseases a paste containing fluorine for dental prophylaxis

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More from Merriam-Webster on prophylaxis

Rhyming Dictionary: Words that rhyme with prophylaxis

Britannica English: Translation of prophylaxis for Arabic Speakers Encyclopedia article about prophylaxis

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