What Is HIV PrEP and How Does It Work?

For individuals at elevated HIV risk without a current diagnosis, pre-exposure prophylaxis (PrEP) may be an appropriate option. Daily adherence to this medication regimen substantially reduces HIV acquisition probability.

Pre-exposure prophylaxis (PrEP) represents a daily pharmaceutical intervention designed to prevent HIV infection onset. This preventive strategy specifically targets HIV-negative individuals facing increased viral exposure risk.

The therapeutic mechanism of PrEP involves HIV transmission risk reduction, providing protective benefits for both users and their partners. This intervention is contraindicated for individuals with existing HIV diagnoses.

Currently, the FDA has approved two distinct antiviral medications for PrEP applications. Consistent daily administration demonstrates significant efficacy in HIV prevention.

Continue reading for comprehensive information regarding PrEP medications and their role in HIV transmission risk mitigation.

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PrEP Overview | Medication Types | Eligibility Criteria | Clinical Efficacy | Safety Profile | Key Takeaways

PrEP’s Mechanism of HIV Prevention

Pre-Exposure Prophylaxis (PrEP) operates through nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs), a class of antiviral agents that inhibit HIV viral replication processes.

Mandatory HIV testing must confirm negative status before PrEP initiation and at minimum quarterly intervals during treatment.

Following potential HIV exposure or acute infection symptoms, PrEP resumption requires confirmed negative test results.

This precaution is critical because PrEP lacks standalone efficacy against established HIV infection and may promote drug resistance if administered during active infection.

PrEP protocols incorporate comprehensive prevention counseling with healthcare providers to:

- Evaluate individual HIV risk factors
- Review available prevention strategies
- Assess potential PrEP integration benefits

Treatment duration varies by individual health circumstances. Consultation with healthcare providers is essential for personalized PrEP duration determination.

FDA-Approved PrEP Medications

The FDA has approved two PrEP medications: Truvada and Descovy. Truvada

Truvada contains emtricitabine and tenofovir disoproxil fumarate active components, available in brand and generic formulations.

This multi-potency medication serves both HIV treatment and prevention indications.

Administered as daily tablets for adults and adolescents ≥35kg (77lbs), Truvada is approved for all genders. Descovy

Descovy similarly combines emtricitabine with tenofovir alafenamide in daily tablet form.

While approved for adults and adolescents ≥35kg, Descovy lacks FDA endorsement for females at HIV risk through vaginal intercourse due to insufficient efficacy data in this population.

PrEP Candidate Profile

CDC data indicate approximately 1.2 million U.S. HIV diagnoses in 2018, with 14% unaware of their status.

PrEP candidates include individuals with recent (past 6 months) anal/vaginal intercourse who:

- Have HIV-positive partners with detectable/unknown viral loads
- Demonstrate inconsistent condom use
- Have recent (≤6 months) STI diagnoses

PrEP is also recommended for injection drug users who:

- Share injection equipment
- Have HIV-positive injection partners

Individuals requiring repeated post-exposure prophylaxis (PEP) with ongoing HIV risk should consult healthcare providers about PrEP initiation.

PrEP Therapy Considerations

Key factors when evaluating PrEP suitability include:

Advantages

- High efficacy with consistent use
- Dual protection for user and partners
- Convenient daily dosing
- Discreet prevention control
- Option for serodiscordant conception

Limitations

- Potential high cost without insurance
- Requires strict adherence
- Mandates quarterly HIV testing
- Possible adverse effects
- Contraindicated with severe renal impairment/hepatitis B history

PrEP Efficacy Data

When taken as prescribed, PrEP demonstrates high HIV prevention efficacy.

CDC reports indicate ≈99% risk reduction for sexual transmission and ≈74% reduction for injection drug use with consistent PrEP use.

Maximal protection requires 7 days of daily PrEP for receptive anal intercourse, extending to 21 days for injection drug use or receptive vaginal intercourse.

Descovy’s efficacy for receptive vaginal intercourse remains unestablished.

PrEP Safety Considerations

While generally safe, Truvada and Descovy may produce adverse effects ranging from mild to severe.

Pre-treatment consultation should address existing health conditions, particularly renal impairment or hepatitis B history, as medication discontinuation may exacerbate hepatitis B.

PrEP is contraindicated for HIV-positive individuals due to potential drug resistance development.

Baseline and quarterly blood testing are required throughout PrEP use.

Potential Adverse Effects

Common effects for both medications include:

- Gastrointestinal disturbances
- Fatigue
- Cephalalgia
- Nausea

Rare serious effects may involve:

- Hypersensitivity reactions
- Hepatorenal complications
- Hepatitis B reactivation
- Metabolic acidosis

This list is not exhaustive. Consult healthcare providers for complete medication information, including potential drug interactions.

Seek immediate medical attention for severe reactions or allergic responses to PrEP medications.

Initiating HIV prevention discussions with healthcare providers is essential for high-risk individuals. Consider these conversation starters:

- Review CDC HIV risk and prevention resources
- Prepare specific questions for providers
- Disclose HIV-related concerns openly
- Inquire about local testing availability
- Discuss PrEP access options
- Explore uninsured patient assistance programs
- Develop partner communication strategies

These discussions enable personalized prevention planning tailored to individual circumstances.

Essential Conclusions

Individuals with potential HIV exposure risk should prioritize regular testing and preventive counseling.

PrEP integration into prevention strategies significantly reduces transmission likelihood through highly effective pharmaceutical intervention.

Proactive health protection begins with consultations at HIV prevention specialty clinics or with knowledgeable healthcare providers.

Section Navigation

PrEP Overview | Medication Types | Eligibility Criteria | Clinical Efficacy | Safety Profile | Key Takeaways