prophylaxis

noun

pro·​phy·​lax·​is ˌprō-fə-ˈlak-səs 

 also  ˌprä-

plural prophylaxes ˌprō-fə-ˈlak-ˌsēz 

 also  ˌprä-

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

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

But as antiretroviral exposure, ART during pregnancy, and pre-exposure prophylaxis (PrEP) reshaped the landscape, the Elton John AIDS Foundation demonstrated agility and shifted its focus to prevention and systemic change. —Jeetendr Sehdev, Forbes, 26 Feb. 2025

People who are exposed to HIV have only 72 hours—less than the amount of time many clinics have now been closed—to begin a medication regimen called post-exposure prophylaxis that can help prevent infection. —Hana Kiros, The Atlantic, 5 Feb. 2025

Even though deaths are rare – fewer than 10 people a year die from rabies in the US – about 60,000 people receive post-exposure prophylaxis after rabies exposure each year. —Carma Hassan, CNN, 3 Dec. 2024

That's well beyond the cut-off date for when post-exposure prophylaxis can be used to prevent infection. —Kristen Jordan Shamus, Detroit Free Press, 12 July 2024

Word History

Etymology

borrowed from New Latin, from Greek prophylak-, stem of prophylássein "to keep guard before a place, be on guard, (middle voice) to be on one's guard against, take precautions against" (from pro- pro- entry 1 + phylássein "to keep watch on, guard, preserve," derivative of phylak-, phýlax "guard, guardian, protector") + -sis -sis — more at phylactery

First Known Use

1683, in the meaning defined above

Phrases Containing prophylaxis

• post-exposure prophylaxis
• preexposure prophylaxis

Rhymes for prophylaxis

• chemotaxis
• epistaxis
• anaphylaxis
• axis
• praxis
• taxus
• chemoprophylaxis

Medical Definition

prophylaxis

noun

pro·​phy·​lax·​is -ˈlak-səs 

plural prophylaxes -ˈlak-ˌsēz 

: 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