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Guide to PrEP Side Effects

Vicky Davis

Medically reviewed by Vicky Davis, FNP

Written by Our Editorial Team

Last updated 8/8/2021

The Centers for Disease Control and Prevention reports that approximately 1.2 million Americans are living with HIV.

If you’re at risk for becoming part of that statistic, daily PrEP can be a hugely helpful medication. Also known as pre-exposure prophylaxis, PrEP can effectively prevent HIV infection.

Like any medication, PrEP does have some side effects, and it’s important to be aware of them before you start taking this medication. But, before we dive into those, learn a bit more about HIV and what PrEP can do for you.

What You Need to Know About HIV

HIV (human immunodeficiency virus) attacks the immune system. When left untreated, it can develop into AIDS (acquired immunodeficiency syndrome). No cure exists for HIV or AIDS.

HIV and AIDS became part of the national discourse when it started rapidly spreading in the United States in the 1980s — particularly among the LGBTQ+ community. 

For a long time, many believed that only members of that specific community could become infected with HIV. But that is completely false — anyone can contract the virus.

When HIV/AIDS first came onto the scene, it was a likely death sentence for anyone infected. Thankfully, medical care and treatment options have come a long way since then, and today, most people with HIV can live long, healthy lives. 

A healthcare provider will use blood, oral fluid or urine tests to accurately determine an HIV diagnosis.

Who is at Risk for HIV

The below bullet points go over who is most at risk for contracting HIV.

  • Homosexual and bisexual men who have sex with men

  • Men and women who consistently do not use condoms during sexual activity

  • Men and women who have sex with HIV-positive persons 

  • People who frequently contract STDs

  • People with multiple sexual partners

  • IV drug users

Men and women who fall into one or more of the above categories may be good candidates to take medications for PrEP, as these are classic risk factors.. 

Facts About PrEP

Before we dive into the side effects of PrEP treatment, here are some things you should know about this preventative medication. 

  • PrEP is offered under the brand names Truvada® and Descovy®.

  • While these medications are only available by prescription in 49 states, they are available as over the counter medications in the state of California.

  • Daily PrEP therapy reduces the risk of getting HIV from sex by 99 percent. While there’s no concrete data for how effective PrEP therapy is in IV drug users, we do know that overall, PrEP is about 74 percent effective.

  • The medication reaches maximum effectiveness from HIV for receptive anal sex at seven days of daily use. 

  • For receptive vaginal sex and IV drug use, PrEP reaches maximum protection at 21 days of daily use.

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Side Effects Associated with Taking PrEP

Like with most medications, there are some side effects associated with taking daily PrEP treatment. That said, a majority of people who take it do not experience any side effects at all.

It’s helpful to know what side effects may occur, just so you won’t be alarmed if you experience any. 

Side Effects During the Start-Up Period 

For those who do experience side effects, it most often happens during the first few weeks of starting PrEP therapy. Thankfully, they are almost always quite manageable.

If an adverse reaction occurs, it's often because PrEP increases liver enzyme levels to fight HIV. In turn, this may slightly affect liver function and cause gastrointestinal distress.

These are the most common side effects experienced during the start-up period of taking daily PrEP: 

  • Headaches

  • Nausea

  • Vomiting

  • Dizziness

  • Loss of appetite

  • Rash

  • Weight gain or loss

  • Abdominal discomfort

  • Tiredness 

Side Effects Connected to Truvada

The different types of PrEP carry different side effects. Truvada is a combo of two drugs — tenofovir disoproxil fumarate and emtricitabine. Both drugs are antiretrovirals that were originally used to treat HIV.

In addition to the start-up side effects, the most common side effects associated with Truvada are:

  • Headaches

  • Stomach pain

  • Weight loss

  • Decrease in bone density

Thankfully, research has shown that this last one is quite mild and reversible with cessation of the drug.

Side Effects Associated with Descovy

Descovy works in a similar way to Truvada. The difference is that it incorporates a newer form of tenofovir called tenofovir alafenamide. There is evidence that Descovy may be slightly more effective at HIV suppression and poses less risk of adversal renal and bone events than Truvada.

This type of PrEP is not approved for people at risk of contracting HIV through receptive vaginal intercourse.

Side effects associated with taking Descovy include diarrhea, nausea, headache, fatigue and stomach issues. More serious side effects are extremely rare, but include an increase of lactic acid in the blood, as well as liver and kidney function issues.

Pay Close Attention to These Side Effects

Before you take PrEP medication, make sure you disclose any preexisting conditions. 

If you start taking PrEP medication and notice a sudden change in your health, reach out to your healthcare provider immediately, as this could be a sign of something serious. Things to watch out for include:

  • Yellowing of the skin or eyes

  • Change of color in urine or stool

  • Intense or excessive abdominal pain

  • Abnormal heartbeat

  • Shortness of breath

  • Bone pain

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The Final Word on the Side Effects of PrEP

PrEP can be an incredibly helpful medication in preventing HIV infection. 

The benefits of PrEP are huge and very much outweigh any potential adverse effects — especially since they are so rare. If you do experience some, it will most likely be during the start-up period and those side effects should only last a few weeks. 

The two types of daily medications for PrEP — Truvada and Descovy — have different side effects associated with them. 

Although extremely rare, there are a few more serious side effects associated with PrEP. If you experience any of them, you should contact a healthcare provider ASAP. 

If you have any further questions about side effects of taking PrEP, speak with a licensed healthcare provider. 

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.