What is the Difference Between PEP and PrEP?

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PrEP and PEP are two methods used to prevent HIV infection using anti-HIV medications. However, they are used in different situations and serve distinct purposes:

  • PrEP (Pre-Exposure Prophylaxis): PrEP is for people who don't already have HIV but are at risk of getting it. It is taken before potential exposure to HIV to reduce the risk of infection. PrEP can be in the form of a daily pill or an injection every two months. If exposed to HIV, the medicine can stop the virus from taking hold and spreading throughout the body.
  • PEP (Post-Exposure Prophylaxis): PEP is for people who have possibly been exposed to HIV and is used only in emergency situations. It must be started within 72 hours after a possible exposure to HIV. PEP is a four-week course of drugs, taken once a day during that time. If taken within 24 hours of exposure to HIV, PEP can significantly reduce the risk of infection.

In summary, the main difference between PrEP and PEP is that PrEP is taken before potential exposure to HIV to prevent infection, while PEP is taken after possible exposure to HIV to reduce the risk of infection.

Comparative Table: PEP vs PrEP

Here is a table comparing the differences between PrEP and PEP:

Feature PrEP (Pre-exposure Prophylaxis) PEP (Post-exposure Prophylaxis)
Timing Taken before potential HIV exposure Taken after potential HIV exposure
purpose Prevent HIV infection before exposure Treat patients who have been exposed to HIV
administration Ongoing, usually daily One-time, 28-day course
medications Truvada and Descovy Truvada, plus a third drug
drug regimen Daily dosing Dosed once a day for 28 days
start time Should be taken before potential HIV exposure Best started within 24 hours of exposure, but no later than 72 hours
duration Continued for as long as the patient is at high risk of HIV exposure The 28-day course is typically used in emergency situations
effectiveness Over 99% effective in preventing HIV transmission Effective in treating patients exposed to HIV, but less effective than PrEP

Both PrEP and PEP are treatment plans intended for people at high risk of HIV transmission but are currently negative for the virus. PrEP is designed for pre-exposure to HIV and is taken continuously to prevent infection, while PEP is used after potential exposure and involves a one-time, 28-day course of treatment. The medications used for both treatments include Truvada, but PEP requires an additional drug due to its different mechanism of action.