HIV Pre-Exposure Prophylaxis (PrEP) is a highly effective preventive medication taken by HIV-negative individuals to significantly reduce the risk of acquiring HIV through sexual contact or injection drug use. When used correctly and consistently, PrEP can lower the risk of HIV infection by up to 99% through sex and at least 74% among people who inject drugs, according to global health authorities.
PrEP is part of a comprehensive HIV prevention strategy that also includes condom use, routine HIV testing, harm-reduction practices, and prompt treatment of people living with HIV. It is recommended by leading public health agencies in the United States, United Kingdom, and globally for individuals at ongoing risk of HIV exposure.
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Pre-Exposure Prophylaxis (PrEP) involves taking antiretroviral medication before potential HIV exposure to prevent the virus from establishing infection in the body. PrEP works by blocking HIV replication if exposure occurs.
PrEP is not a cure for HIV and does not replace other preventive measures, but it is one of the most powerful tools available for HIV prevention when used appropriately.
PrEP is intended for people who do not have HIV but are at increased risk of HIV exposure through sexual contact or injection drug use. PrEP is not appropriate for people who are already living with HIV.
According to the Centers for Disease Control and Prevention (CDC), you should consider PrEP if you are HIV-negative, have engaged in anal or vaginal sex within the past six months, and meet one or more of the following risk categories:
You are in a sexual relationship with an HIV-positive partner, especially if condoms are not consistently used
You have sexual partners of unknown HIV status, particularly in regions with higher HIV prevalence
You have multiple sexual partners and do not consistently use condoms
You inject drugs and share needles, syringes, or other injection equipment
You have had a recent sexually transmitted infection (STI), which increases HIV risk
Ensure you talk to your health care provider if you think PrEP may be right for you, and a confirmed negative HIV test is mandatory before starting PrEP.
The most common PrEP regimens include:
F/TDF (Tenofovir disoproxil fumarate 300 mg / Emtricitabine 200 mg)
Brand name: Truvada®
To be taken once daily. Not recommended for individuals with eGFR < 60 mL/min due to kidney risks.
F/TAF (Tenofovir alafenamide 25 mg / Emtricitabine 200 mg)
Brand name: Descovy®
To be taken once daily. Has a better kidney and bone safety profile, but is not approved for individuals at risk through receptive vaginal sex.
Daily dosing is the only method approved and recommended by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA) for oral PrEP to effectively prevent HIV infection.
Individuals using injectable PrEP receive long-acting antiretroviral injections at regular intervals, depending on the medication:
Cabotegravir (Apretude®) is administered every eight weeks
Currently, cabotegravir (Apretude®) is the only FDA-approved long-acting injectable PrEP option. Other long-acting agents are under investigation or approved in limited settings.
Some injectable PrEP regimens may require a short course of oral tablets at the start of treatment, as directed by a healthcare provider.
Read Also: Navigating the World of Sexual Health: Common STIs and Prevention
Some individuals may consider on-demand (event-based) PrEP, which is taken around the time of sexual activity rather than daily. However, this approach is not recommended by the CDC or FDA and should only be used under the guidance of a qualified healthcare provider.
On-demand PrEP follows a scheduled dose of “2-1-1” dosing, which involves:
Taking two tablets 2 to 24 hours before sex
Taking one tablet 24 hours after the first dose
Taking one final tablet 24 hours after the second dose
It is important not to miss any scheduled doses, whether taking PrEP as daily tablets or as injections. PrEP is significantly less effective when not taken as prescribed, increasing the risk of HIV infection and the development of HIV drug resistance.
People taking PrEP should:
Undergo HIV testing every 3 months
Have regular kidney function monitoring
Be screened periodically for sexually transmitted infections
This routine follow-up ensures PrEP remains safe and effective.
PrEP is generally well tolerated. Mild side effects may include:
Nausea
Headache
Diarrhea
Abdominal discomfort
Long-term use of TDF-based PrEP may affect kidney function and bone density, particularly in individuals with existing risk factors. TAF-based PrEP is considered safer for bones and kidneys.
NSAIDs (e.g., ibuprofen, diclofenac, naproxen) should be used with caution, especially with TDF-based PrEP, due to potential kidney effects.
PrEP does not interact significantly with alcohol or recreational drugs, but moderation is advised.
PrEP does not prevent pregnancy and can be safely used alongside Hormonal contraceptives and Non-hormonal birth control methods. PrEP may be used during pregnancy and breastfeeding when HIV risk is present, as drug levels in breast milk are low and considered safe.
No. PrEP only prevents HIV. It does not protect against Gonorrhea, Chlamydia, Syphilis, Herpes and Trichomoniasis. Consistent condom use remains essential for STI prevention.
PrEP may be discontinued:
After 28 days following the last potential HIV exposure
When HIV risk is no longer present
Individuals should continue safe sex practices and avoid high-risk behaviors after stopping PrEP. An HIV-positive person who maintains a sustained undetectable viral load cannot transmit HIV sexually (It simply means U=U).
HIV Pre-Exposure Prophylaxis (PrEP) is a preventive medication taken by HIV-negative individuals to significantly reduce the risk of getting HIV through sexual contact or injection drug use.
When taken correctly and consistently, PrEP reduces the risk of HIV infection by up to 99% through sex and at least 74% among people who inject drugs.
PrEP is recommended for people at high risk of HIV, including those with an HIV-positive partner, individuals with multiple sexual partners, people who do not consistently use condoms, and people who share injection equipment.
PrEP reaches maximum protection after:
7 days for receptive anal sex
21 days for receptive vaginal sex and injection drug use
Daily adherence is essential for full effectiveness.
Most people tolerate PrEP well. Common mild side effects include nausea, headache, diarrhea, and fatigue. Long-term use of some PrEP medications may affect kidney function or bone density, which is why regular monitoring is recommended.
No. PrEP only protects against HIV. It does not prevent STIs such as gonorrhea, chlamydia, syphilis, or herpes. Condom use remains important for STI prevention.
Yes. Clinical studies and real-world use show that PrEP is safe for long-term use when taken under medical supervision with routine HIV testing and kidney function monitoring.
PrEP can be stopped when HIV risk is no longer present. Experts recommend continuing PrEP for 28 days after the last potential HIV exposure before discontinuation and maintaining safe-sex practices afterward.
Additional reading from pharmacy education platforms such as Pharmchoices.com may provide practical insights, but clinical guidance should always follow CDC, WHO, or national health authority recommendations.
This article is for educational purposes only and does not replace professional medical advice. Always consult a qualified healthcare provider before starting or stopping PrEP.
