Woman using laptop to learn how Truvada® works

How does Truvada® work?

Written on May 22, 2023 by Gillian (Gigi) Singer, MPH, Sexuality Educator & Certified Sexologist. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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In recent years, the development of various preventive measures has played a significant role in promoting sexual health and reducing the transmission of sexually transmitted infections (STIs) and Human Immunodeficiency Virus (HIV). One of these breakthroughs was in the field of HIV prevention and is a medication called Truvada®, which reduces the risk of HIV transmission.

Spotlight on Truvada®

Truvada® is one of the three forms of Pre-Exposure Prophylaxis (PrEP) available for use at this time. PrEP is a medication that can prevent the transmission of Human Immunodeficiency Virus (HIV) if and/or when a person is exposed to the virus.

The FDA has approved three medications as forms of PrEP: Truvada®, Descovy®, and Apretude®:

  • Truvada® is in the form of a pill and “is for all people at risk for HIV through sex or injection drug use.”[1] It is taken once per day.
  • Descovy® is also a pill and “is for sexually active men and transgender women at risk of getting HIV. Descovy® is not for people assigned female at birth who are at risk for HIV through receptive vaginal sex.”[1]
  • Unlike the other two, Apretude® is a “long-acting injectable form of PrEP” approved “for people at risk for HIV through sex who weigh at least 77 pounds (35 kg.) It is administered by a health care provider every two months instead of daily oral pills.”[1]

How Truvada® works

You may wonder, how does Truvada® work? Truvada® is what’s called an antiretroviral medication, commonly referred to as ART. This medication combines two active ingredients: tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC). Truvada®, when in the system and used properly, inhibits the replication of HIV within the body, thus reducing the risk of the virus establishing itself in the body.[2]

HIV establishes itself in a body by essentially attacking the immune system, the cells that work to fight infections, and then multiplies and integrates itself into the host's DNA. “The 2 medications that make up Truvada® (tenofovir and emtricitabine) block important pathways that viruses use to set up infection,” says the CDC.[2] Truvada® functions by targeting two crucial enzymes essential for HIV replication: reverse transcriptase and integrase. By blocking these enzymes, Truvada® interferes with the virus's ability to multiply and integrate itself into the host's DNA. This disruption hinders the virus's ability to establish a productive infection, significantly reducing the risk of HIV transmission.

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Effectiveness and usage

Truvada® has been extensively studied and has shown remarkable effectiveness in reducing the risk of HIV transmission when used as directed. Taking Truvada® daily can lower a person’s risk of getting HIV from sex by more than 99%, and for people who inject drugs, Truvada® reduces the risk of contracting HIV by more than 74%.[3]

PrEP is less effective when it isn’t taken daily and will not prevent pregnancy or other STIs/STDs. PrEP, when combined with other safer sex practices, will contribute greatly to keeping you healthy.

Starting Truvada®

Truvada® is not available over the counter and must be prescribed by a healthcare provider (HCP). Before you begin taking any form of PrEP, you will need to be tested for HIV to make sure you are not already HIV positive. You will return to your HCP every three months for HIV testing if you are actively taking PrEP.[4]

When you talk to your HCP about PrEP/Truvada®, they can also counsel you on safer sex practices and harm reduction practices.

Side Effects

Like any medication, Truvada® may have side effects that vary from person to person. Common side effects may include nausea, headaches, vomiting, and loss of appetite. These side effects are usually mild and go away over time.[2]

If you experience fever or chills, sore throat, cough, rash, or other signs of a potential infection, you should consult your HCP as soon as possible.[2]

Who should and shouldn’t take Truvada®

It is important to consult a healthcare professional before starting Truvada® to assess individual risk factors and address any concerns. If you are living with other health concerns or conditions or take other medications or supplements, you should tell your HCP in case there will be an interaction with Truvada®.

Anyone who is at risk of contracting HIV might consider taking Truvada® or another form of PrEP to prevent subsequent transmission and infection. Some ways you might be at increased risk of HIV include if you have many sexual partners whose HIV status is unknown, have one or more sexual partner who is HIV positive, use injectable drugs, or engage in sex work.

People who are unlikely to be able to take Truvada® every day should talk to an HCP about alternatives, like injectable Apretude® (if you are eligible).

It is vital to remember that Truvada® is not a substitute for other preventive measures, such as condom use and regular testing. Combining Truvada® with comprehensive sexual health practices can significantly enhance overall protection against HIV and promote a sex-positive approach to health and well-being.

Remember, always consult with a healthcare professional for personalized advice regarding sexual health and the use of Truvada®.

To speak with a healthcare provider about HIV prevention and/or treatment, book an appointment through Everlywell's STD telehealth option.

How effective is Truvada® in preventing HIV?

What is Apretude®? Everything you need to know

PrEP for HIV prevention: how it works and more


  1. Pre-exposure prophylaxis: Prep medication. HIV.gov. https://www.hiv.gov/hiv-basics/hiv-prevention/using-hiv-medication-to-reduce-risk/pre-exposure-prophylaxi. Accessed May 18, 2023.
  2. Truvada Medication Information Sheet for Patients. https://www.cdc.gov/hiv/pdf/prep_gl_patient_factsheet_truvada_english.pdf. Accessed May 18, 2023.
  3. US Public Health Service: Preexposure prophylaxis for the prevention of HIV infection in the United States. Centers for Disease Control and Prevention. 2021. https://www.cdc.gov/hiv/pdf/risk/prep/cdc-hiv-prep-guidelines-2021.pdf. Accessed May 18, 2023.
  4. PrEP: How effective is it at preventing HIV? Mayo Clinic. May 14, 2021. https://www.mayoclinic.org/diseases-conditions/hiv-aids/expert-answers/prep-hiv/faq-20456940. Accessed May 18, 2023.
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