The HARNESS Project
← Back to Blog

What is PrEP? A Complete Guide to HIV Prevention

Complete guide to PrEP for HIV prevention: how it works, who should take it, side effects, cost, access, and common questions. Evidence-based information for empowered decisions.

By The HARNESS Project • February 1, 2026 • 8 min read

What Exactly is PrEP?

PrEP stands for Pre-Exposure Prophylaxis. It’s a medication that helps prevent HIV infection in people who don’t have HIV but are at substantial risk of getting it.

Think of it this way: if you’re sexually active and at risk for HIV, PrEP acts like a protective shield. When taken as prescribed, it’s remarkably effective—up to 99% when taken daily.

What is PrEP? PrEP is a daily medication (or injectable) containing antiretroviral drugs (tenofovir and emtricitabine) that prevents HIV infection with 99% effectiveness when taken as prescribed. It’s designed for people at substantial risk of HIV exposure who aren’t currently infected.

The Science Behind PrEP

PrEP typically contains two antiretroviral drugs: tenofovir and emtricitabine (Truvada is the most common brand, though generic versions are available). These medications work by blocking enzymes that HIV needs to replicate in your body.

How it works:

  1. You take the medication before potential exposure to HIV
  2. The drug levels build up in your body tissues
  3. If HIV enters your body, the medication prevents it from replicating
  4. Your immune system can then clear the infection

Who Should Consider PrEP?

You might be a candidate for PrEP if you:

  • Are sexually active with partners of unknown or positive HIV status
  • Have a partner with HIV (especially if they’re not virally suppressed)
  • Have had an STI in the past 6 months
  • Don’t consistently use condoms
  • Have engaged in transactional sex
  • Are a sex worker or partner of a sex worker
  • Use substances during sex
  • Are a man who has sex with men
  • Are a transgender person with specific risk factors

The key question: Do you think there’s any chance you could be exposed to HIV in the next 3 months?

If yes, talk to a healthcare provider about PrEP.

Effectiveness: The Numbers You Need to Know

When taken correctly, PrEP is highly effective:

  • 99% effective at preventing HIV from sexual transmission when taken daily
  • 74% effective for people who take it inconsistently
  • 96-98% effective when taken 4-5 times per week

Important note: These numbers come from major studies like IPERGAY and the Randomized Controlled Trials (RCTs) funded by the NIH.

How effective is PrEP at preventing HIV? PrEP is 99% effective at preventing HIV transmission when taken daily as prescribed. For inconsistent use, effectiveness ranges from 74-96% depending on frequency. Long-acting injectables (Cabotegravir) show 98%+ effectiveness with better adherence rates.

New in 2026: PrEP Evolution

Cabotegravir (Apretude) - The Game-Changing Injectable

The newest breakthrough in PrEP is long-acting cabotegravir (Apretude)—an injection given every two months instead of a daily pill.

Key advantages:

  • Set-and-forget: 98%+ effective with near-zero adherence burden
  • Privacy: No daily pill, making it easier for people in unsupportive environments
  • Confidence: Consistent drug levels eliminate fluctuation concerns
  • Efficacy: Slightly higher effectiveness than daily pills in real-world use

Considerations:

  • Still newer (FDA approved 2023)
  • Less accessible than oral PrEP
  • More expensive initially
  • Requires clinic visits every 2 months

Lenacapavir (Sunlenca) - The Newest Option

Even more recent is lenacapavir, a new-generation HIV preventative injected twice yearly:

  • Ultra-long-acting: Every 6 months instead of 2 months
  • Highest efficacy: 98%+ in clinical trials
  • Future-forward: Represents the next generation of prevention
  • Limited availability: Not yet widely available in all regions

What this means: By 2026, people choosing PrEP have more options than ever—daily pills, bimonthly injections, and now twice-yearly options. The choice is increasingly flexible.

Types of PrEP

Daily PrEP (Most Common)

  • You take one pill every day
  • Requires consistent adherence
  • Works for all types of exposure

On-Demand PrEP (Event-Driven)

  • Take 2 pills 2-24 hours before sex
  • Then 1 pill 24 hours later and 1 pill 48 hours later
  • Only works for receptive anal sex
  • Doesn’t protect against other STIs

Long-Acting Injectable PrEP (Cabotegravir)

  • Injection every 2 months
  • No daily pill to remember
  • Highest adherence rates
  • Still newer and less accessible

Common Side Effects

Most people tolerate PrEP well. Common side effects include:

  • Nausea (usually mild and temporary)
  • Headaches
  • Abdominal discomfort
  • Fatigue (rare)

These typically go away after 2-4 weeks.

Serious Side Effects (Rare)

  • Kidney issues (monitored through regular testing)
  • Bone density changes (monitored in long-term users)
  • Liver concerns (more common in people with existing liver disease)

Regular monitoring is key. You’ll need:

  • Kidney function tests
  • HIV tests
  • STI screening
  • Liver function tests (if indicated)

Cost and Insurance Coverage

In the US:

  • Brand name Truvada: $1,200-$1,600/month
  • Generic versions: $20-$50/month
  • Good news: Most insurance plans cover it
  • Uninsured: Programs like AIDSVU and PrEP assistance programs offer free or low-cost options

Globally:

  • Access varies dramatically by country
  • Generic versions are much cheaper in many countries
  • Some countries have government-funded programs

How to Get PrEP

Step 1: Find a Provider

  • Your primary care doctor
  • Sexual health clinics
  • LGBTQ+ health centers
  • Telehealth services (Nurx, MISTR, Folx Health)

Step 2: Initial Appointment

  • Discuss your risk factors
  • Get tested for HIV (must be negative)
  • Get baseline kidney and liver function tests
  • Discuss side effects and adherence

Step 3: Start the Medication

  • Get your first prescription
  • Start taking it daily (or as directed)
  • Schedule follow-up in 1-3 months

Step 4: Ongoing Care

  • Regular STI testing (every 3 months)
  • Kidney function monitoring (every 6-12 months)
  • HIV testing (every 6 months)
  • Adherence check-ins

PrEP + Other Protection

Here’s the truth: PrEP is powerful, but it’s even better when combined with other strategies.

Combination Approaches:

  • PrEP + Condoms = Maximum STI prevention + HIV prevention
  • PrEP + Testing = Early detection if infection occurs
  • PrEP + Communication = Knowing your partner’s status
  • PrEP + Therapy = Addressing substance use or sexual trauma

Common Questions About PrEP

”Will taking PrEP daily damage my kidneys?”

For most people, no. But regular monitoring is important. People with existing kidney disease need extra caution.

”Does PrEP work for anal, vaginal, and oral sex?”

Yes, it’s effective for all types of sexual transmission. It does NOT prevent pregnancy or other STIs.

”What if I forget a dose?”

Effectiveness drops significantly. This is why long-acting injectables are becoming popular—they remove the adherence challenge.

”Can I become resistant to the medication?”

Only if you take it while HIV-positive. If you’re HIV-negative, resistance isn’t a concern.

”Will my partner know I’m on PrEP?”

Only if you tell them. It’s a private health decision.

”Is PrEP only for gay men?”

No. Anyone at risk for HIV can use PrEP. This includes straight people, women, people who use drugs, sex workers, and more.

The Emotional Side of PrEP

Beyond the medical facts, PrEP represents a shift in how we think about sexual health.

PrEP empowers you to:

  • Take control of your health
  • Be sexually active without fear
  • Make informed choices about your body
  • Challenge shame and stigma
  • Build healthier relationships

For Relationships:

  • Reduces anxiety about transmission risk
  • Can improve sexual enjoyment
  • Enables honest conversations about safer sex
  • Removes “what if” fears

Related: Explore our comprehensive MATCH Framework to integrate PrEP into your complete sexual health plan across Medications, Awareness, Tools, Communication, and Habits.

Build Your Personalized PrEP Plan

Ready to take action? Use our interactive tools to create your personalized sexual health strategy:

  • My Condom Plan - Choose condom types and sizes that work best for you as a backup protection method alongside PrEP
  • MATCH Framework Tool - Map out all five pillars of your sexual health, including whether PrEP fits your plan
  • Conversation Starters - Find scripts for discussing PrEP with partners and healthcare providers
  • Complete Resources Hub - Access all HARNESS sexual health education tools and curricula

Explore PrEP in Different Contexts:

Not sure how PrEP compares to other prevention methods? Read our detailed PrEP vs. Traditional HIV Prevention comparison to see which approach works best for your lifestyle.

In a relationship and considering PrEP together? Discover how PrEP is transforming long-term relationships and real stories from couples using PrEP as relationship wellness.

Building your pleasure-positive approach? Learn more in our detailed guide on why traditional “safe sex” messaging is outdated and how to build a SafER sex strategy using combination prevention.

The Bottom Line

PrEP is a game-changing prevention tool. If you’re sexually active and at risk for HIV, talking to a healthcare provider about PrEP could be one of the most important health decisions you make.

Remember:

  • PrEP is 99% effective when taken correctly
  • It’s well-tolerated for most people
  • It’s increasingly affordable
  • It’s becoming easier to access
  • It’s a sign of self-respect and power

Ready to Learn More?

HARNESS Resources:

External Resources:

Questions about PrEP? Talk to your healthcare provider, or reach out to a sexual health clinic near you.

The HARNESS Project believes everyone deserves fearless, protected, empowered connections.

Share this article: