How Does HIV PrEP Work? How Does HIV PrEP Work?

How Does HIV PrEP Work?


PrEP is a once-daily medication used to prevent the development of HIV cases. It is intended for people who do not currently have HIV but have a higher risk of contracting it.

PrEP reduces your risk of developing HIV by protecting you and your partners from infection. It is not intended for people who are currently living with HIV.

Today, the FDA has approved two different antiviral medications for PrEP. They are highly effective at preventing HIV infection when taken regularly.

Please continue reading to learn more about PrEP medications and their role in reducing the risk of contracting HIV.

How Does PrEP Work In Terms Of HIV Prevention?

PrEP medications are classified as nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs). They work by inhibiting the virus's replication within your body.

Before initiating PrEP and at least every three months after that, you must be tested for HIV and negative results.

If you have been exposed to HIV or exhibit acute HIV symptoms, you will wait until you test negative before restarting your PrEP medication.

It is critical to wait for a negative test result because PrEP cannot treat HIV effectively, and drug resistance may develop if PrEP is used during an HIV infection.

Counselling for prevention is another critical component of PrEP. Before initiating PrEP therapy, a healthcare professional can assist you in the following ways:


  • To gain a better understanding of your risk of contracting HIV

  • Prevention methods

  • Why it may be advantageous to incorporate PrEP into your daily routine


Your health factors will determine the duration of your PrEP treatment. Consult a healthcare provider about your health history and the time of your PrEP treatment.

What Are The Various Forms Of PrEP?

Truvada and Descovy are the two approved PrEP medications.


Emtricitabine and tenofovir disoproxil fumarate are the active ingredients in Truvada. It is available as a brand-name medication as well as a generic medication.

Truvada is available in various strengths and is prescribed for HIV treatment or pre-exposure prophylaxis.

Truvada is available in tablet form and should be taken daily by adults and adolescents weighing at least 35 kilograms (around 77 pounds). It is safe and effective in both males and females.


Descovy is also a once-daily tablet. Emtricitabine and tenofovir alafenamide are the active ingredients.

Adults and adolescents weighing at least 35 kilograms may use Descovy (77 pounds). Descovy is not approved for use by females at a higher risk of contracting HIV through vaginal sex, as its effectiveness in this group has not been established.

Who Is A Possible Candidate For PrEP?


Individuals who have had anal or vaginal sex in the last six months and those who:


  • Have a sexual partner who is HIV positive with a detectable viral load or an unknown viral load

  • Have not consistently used a condom during sex

  • Have been infected with a sexually transmitted infection (STI) in the preceding six months

Additionally, it is recommended for individuals who inject drugs and:

  • Share needles (syringes)

  • Have an HIV-positive injection partner

If you have been prescribed post-exposure prophylaxis (PEP) multiple times and your risk of developing HIV increases, speak with a healthcare professional about starting PrEP.


The Advantages And Disadvantages Of HIV PrEP Therapy

Numerous factors must be considered when initiating a new medication. Consider the following factors when determining whether PrEP is right for you:


  • When taken regularly, the medications are highly effective at preventing HIV cases.

  • They can help prevent HIV transmission between you and your partner.

  • It is convenient because it is a single pill taken once daily.

  • It is discrete and empowers individuals to control their prevention, particularly those with a higher risk of contracting HIV.

  • It is a viable option for serodiscordant individuals (those with mixed HIV) who wish to conceive.


  • Truvada and Descovy brand-name medications can be prohibitively expensive, particularly without insurance.

  • It would be beneficial if you remembered to take it daily.

  • You must submit to regular HIV testing (at least every three months).

  • These medications may cause adverse reactions (see safety section below).

  • If you have a severe kidney condition or a history of hepatitis B, this medication may not be appropriate for you.

Is PrEP Effective Against HIV?

When taken on a regular schedule as prescribed by a doctor, PrEP is highly effective at preventing HIV.

According to the CDC, when taken regularly, these medications reduce the risk of contracting HIV from sex by approximately 99% and about 74% in people who inject drugs.

However, the medications listed above are not immediately effective. They must be taken daily for at least seven days to provide maximum protection against HIV transmission during receptive anal sex.

Maximum protection occurs after approximately 21 days of daily use of injection drugs or receptive vaginal sex.

Bear in mind that the efficacy of Descovy has not been established in females who have receptive vaginal sex.


Is PrEP For HIV Safe?

Truvada and Descovy are safe, but some individuals may experience adverse effects. Several of these negative effects may be severe.

Consult a healthcare professional before initiating Descovy or Truvada for PrEP to discuss any health conditions you may have and the potential side effects and benefits of PrEP. For instance, you may not take these medications if you have severe kidney disease.

Additionally, inform your doctor if you have ever had hepatitis B. Withdrawing from Truvada or Descovy may exacerbate a hepatitis B infection.

A healthcare professional will monitor your liver function and treat recurrent hepatitis B infections.

It is critical to avoid PrEP medications if you have HIV. If you take the drug while living with HIV, the medicine may develop resistance to the virus.

You will undergo a blood test before beginning the medication and at least every three months while on it.


Possible Side Effects

The following are some of the more common side effects of both medications:

  • Nausea

  • Headache

  • Fatigue (tiredness)

  • Diarrhea

Both have rare but severe side effects, including the following:

  • Lactic acidosis (too much lactic acid in the blood)

  • Worsening hepatitis B case

  • Liver and kidney problems

  • Rash (allergic reaction)

These are not all of the possible Truvada and Descovy side effects. Consult a healthcare professional or pharmacist for additional information about these medications, including possible interactions with other prescription or OTC medications you take.

If you have an allergic reaction or another severe side effect from PrEP medications, immediately call 112 or go to an emergency medical centre.


Establishing The Conversation

If you believe you may have an increased risk of developing HIV, it is critical to discuss this with a trained healthcare professional and take steps to protect yourself from HIV.

Here are some suggestions for igniting a meaningful discussion:


  • Discover the risk of contracting HIV from reputable sources such as the CDC.

  • Prepare a list of questions to ask a counsellor or healthcare professional.

  • Communicate honestly and openly about your concerns about HIV and your health experience.

  • Inquire as to where you can receive routine testing.

  • Inquire about PrEP medication availability in your area.

  • If you do not have health insurance, specific state health departments provide free PrEP.

  • Discuss how to communicate with sexual partners about your concerns about contracting HIV.

The Bottom Line

If you believe you may be at risk of contracting HIV, you must undergo routine testing and speak with a counsellor or healthcare professional about possible prevention measures.

PrEP may be included as part of your prevention strategy. HIV PrEP is a highly effective medication regimen that can significantly reduce your risk of contracting HIV and transmitting it to sexual partners.

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