Illustration of HIV particles while Descovy® begins to take effect

How long does it take for Descovy® to become effective?

Written on May 22, 2023 by Lori Mulligan, MPH. 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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Before revealing how long it takes for Descovy®, an oral HIV antiviral, to become effective, it is essential to know a few key points. It is useful to know why we need Descovy®, its contribution to pre-exposure prophylaxis (PrEP), and its characteristics.

Why do we need Descovy®?

When you consider both the progress and the ongoing challenges in ending the HIV pandemic, you will understand why we need Descovy® and the important role it plays in HIV prevention.

Consider the following global HIV statistics [1]:

  • 38.4 million [33.9 million–43.8 million] people globally were living with HIV in 2021.
  • 1.5 million [1.1 million–2.0 million] people became newly infected with HIV in 2021.
  • 650 000 [510 000–860 000] people died from AIDS-related illnesses in 2021.
  • 28.7 million people were accessing antiretroviral therapy in 2021.
  • 84.2 million [64.0 million–113.0 million] people have become infected with HIV since the start of the epidemic.
  • 40.1 million [33.6 million–48.6 million] people have died from AIDS-related illnesses since the start of the epidemic.

And here are some statistics on new HIV infections [1]:

  • New HIV infections have been reduced by 54% since the peak in 1996.
  • In 2021, around 1.5 million [1.1 million–2.0 million] people were newly infected with HIV, compared to 3.2 million [2.4 million–4.3 million] people in 1996.
  • Women and girls accounted for 49% of all new infections in 2021.
  • Since 2010, new HIV infections have declined by 32%, from 2.2 million [1.7 million–2.9 million] to 1.5 million [1.1 million–2.0 million] in 2021.
  • Since 2010, new HIV infections among children have declined by 52%, from 320 000 [220 000–480 000] in 2010 to 160 000 [110 000–230 000] in 2021.

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How does Descovy® contribute to PrEP?

PrEP is a selection of FDA-approved medicines that are used to prevent HIV infection in at-risk adults and adolescents. When taken as prescribed, PrEP is highly effective for preventing HIV.

PrEP involves taking the combination drug emtricitabine-tenofovir (Truvada®) or emtricitabine plus tenofovir alafenamide (Descovy®) every day.

An injection of cabotegravir (Apertude®) is also available for PrEP and is recommended for high-risk adults and adolescents who have a bad reaction to oral medications or have trouble adhering to the daily pill schedule.[2]

Who is eligible for Descovy®?

Descovy® for PrEP is an oral pill for those at risk of getting HIV through sex, but it’s not for everyone.

Because there has been a lack of clinical studies, Descovy® is not for people assigned female at birth who are at risk for HIV through receptive vaginal sex.[3]

Is Descovy® safe?

Studies have shown that Descovy® is safe. No significant health effects have been seen in people who are HIV-negative.

Some people taking Descovy® may have side effects like nausea, diarrhea, headache, fatigue, and stomach pain.

These side effects are usually not serious and go away over time. If you are taking PrEP, tell your healthcare provider if you have any side effects that bother you or that do not go away.

And be aware: PrEP protects you against HIV but not against other sexually transmitted infections (STIs) or other types of infections. Combining PrEP with condoms will reduce your risk of getting other STIs.[4]

How long does it take for Descovy® to become effective?

For receptive anal sex (bottoming), Descovy® pills reach maximum protection from HIV at about seven days of daily use. No data are available for Descovy® pill effectiveness for insertive anal sex (topping) or insertive vaginal sex.[5]

What are the requirements for ongoing use?

You will need a negative HIV test before you start taking PrEP and then every three months as long as you’re taking it.

What is the regimen for maintaining Descovy®?

PrEP involves taking Descovy® every day. Having PrEP medicine in your bloodstream can stop HIV from taking hold and spreading in your body.[6]

The future of PrEP

The following are goals for the future of PrEP:

  • Expand PrEP use, specifically conduct clinical trials testing effectiveness of Descovy® in assigned females at birth
  • Increase awareness through public health campaigns
  • Encourage healthcare providers to discuss PrEP
  • Destigmatize PrEP use, and
  • Promote racial/ethnic equity in PrEP access

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What is Descovy® used for?

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How effective is Truvada® in preventing HIV?


  1. Global HIV & AIDS statistics — Fact sheet. UNAIDS. Accessed on May 18, 2023.
  2. About PrEP. CDC. June 30, 2022. Accessed on May 17, 2023.
  3. PrEP: How effective is it at preventing HIV? — Expert answers. Mayo Clinic. Accessed on May 17, 2023.
  4. Using HIV medication to reduce risk PrEP. Accessed on May 17, 2023.
  5. How effective is PrEP? CDC. Accessed on May 17, 2023.
  6. Pre-exposure prophylaxis. NIH. Accessed on May 18, 2023.
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