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How effective is PrEP in preventing HIV infections?

Otherwise known as pre-exposure prophylaxis, PrEP is given as a medication to prevent HIV infections in those who are at high risk. If you have regular sex with someone who has HIV, you don’t always use condoms, you’ve had an STI in the past, or you have sex or share needles with someone who injects drugs, PrEP may be right for you. But how effective is PrEP?

PrEP is currently available as one of the following two medications: Truvada and Descovy. Truvada contains tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) while Descovy contains tenofovir alafenamide (TAF) and emtricitabine (FTC). Clinical trials have shown that PrEP medications are highly effective for preventing HIV infection. However, it’s important to remember that PrEP effectiveness is also dependent on taking the drug correctly without missing any necessary doses.   

Continue reading to learn more about the effectiveness of PrEP, and how it might be right for you. 

How effective is PrEP?

For those who may be at risk of getting HIV from sex, PrEP is more than 90% effective. More specifically, data suggests that PrEP is 99% effective for preventing HIV from anal and vaginal sex, whether it’s receptive (bottom) or insertive (top). PrEP is also at least 74% for preventing HIV infection in people who inject drugs (PWID). 

You may experience decreased PrEP effectiveness if the medication is not taken correctly. For instance, those who skip doses or forget to take it may be at a higher risk of getting HIV than those who take PrEP as directed. One clinical trial found that PrEP reduces the risk of HIV by 99% when seven daily doses are taken every week, 96% when four daily doses are taken every week, and 76% when two daily doses are taken every week. 

Other studies have suggested that PrEP effectiveness can vary. For example, one study showed a more modest PrEP effectiveness of 92% when PrEP is taken daily in men who have sex with men. Another study, called the PROUD study, conducted in the UK, showed an effectiveness of 86% for preventing HIV infection in people taking PrEP daily. Other factors may affect how well PrEP works, such as missing a dose, drug interactions, and the types of at-risk behaviors being performed. 

Different ways of taking PrEP

There are different ways of taking PrEP since it can be taken daily or on-demand. How effective is PrEP when taken on demand? Taking PrEP on demand has been shown to be just as effective as daily PrEP. Those who take on-demand, or event-based PrEP, would only take PrEP as needed if they don’t have sex as often or if they’re able to predict when they will have sex. This method involves taking an initial dose of PrEP between 2 and 24 hours before sex and then a single dose for 2 days following sex. 

To ensure maximum PrEP effectiveness, it’s important to take PrEP at the same time each day. You might choose to take it during the morning or evening, as long as it’s around the same time as when you took it the previous day. It’s best to make PrEP a part of your daily habits. For example, you might take it after you eat breakfast or before you brush your teeth during bedtime. Keep in mind PrEP can be taken with or without food. 

How does PrEP work?

PrEP works by stopping HIV from being able to copy itself and spread throughout the body. Normally, the virus attacks immune cells called T-cells. The virus injects its genetic material into a healthy cell and uses an protein enzyme called reverse transcriptase to create DNA. This viral DNA is then used to create the building blocks of the virus inside an infected T-cell. Once copies of the virus are made, the virus can spread to other immune cells. 

When does prep become effective?

You might be wondering how long until PrEP is effective. It typically takes around 7 days of consistent daily use for PrEP to be effective for preventing HIV transmission from receptive anal sex, or bottoming. It can take around 21 days of daily use for PrEP to be the most effective for preventing HIV from receptive vaginal sex and drug injections. Not enough data is available on when PrEP becomes effective for insertive vaginal sex and insertive anal sex (topping). 

Event-based PrEP should be effective when taken 2 to 24 hours before sex. However, follow-up doses are needed for the following two days after sex in order to provide maximum PrEP effectiveness. 

As long as you don’t miss more than three doses per week, you should be protected from HIV during anal sex. You shouldn’t miss more than one dose per week if you’re having vaginal sex. Otherwise, it’s important to follow your dosing schedule and take PrEP effectively. 

Can you get HIV with PrEP?

So, how effective is PrEP for preventing HIV while on treatment? The risk of getting HIV with PrEP is extremely low. Those who get HIV while using PrEP are often those who miss or skip a dose. That’s why it’s important to take PrEP every single day as directed. You’ll get maximum PrEP effectiveness and reduce your risk of HIV as much as possible when taking it correctly.

How effective is PrEP after 2 days?

Men who have sex with men receive maximum PrEP effectiveness after 7 days of daily use. It can take 21 days for PrEP to be effective for vaginal sex and injection drug use. PrEP may not be fully effective after only a few days of taking it. For this reason, it’s important to use PrEP with other methods of protection, such as condoms, at least for the first week. You may be at risk of getting HIV if you engage in risky activities after taking PrEP for only 1, 2, or 3 days. This is because the drug needs time to build up to consistent levels in the blood in order to provide maximum protection.

How effective is PrEP after exposure?

PrEP refers to antiviral medications used before exposure to prevent HIV infections. Post-exposure prophylaxis, or PEP, refers to taking antiviral medications after you’ve been exposed during risky activities. PEP may consist of similar medications to those used for PrEP.

PEP is most effective when taken within 72 hours after exposure. You may have to take a combination of three antiviral medications two to three times per day for 28 days, or 4 weeks, after exposure. When taken correctly, PEP is more than 80% effective for reducing the risk of HIV. There is not enough evidence to say that PEP is highly effective for preventing HIV from injection drug use. If you use injectable drugs or know you’ll be potentially exposed to HIV on a regular basis, PrEP may be an option for you. You can safely transition from PEP to PrEP if needed. 

How effective is PrEP without condoms?

If you’re wondering how effective prep is without condoms, the answer is it depends. You should use condoms for 7 days after starting PrEP if you are having anal sex. You should also use condoms for 21 days after starting PrEP if you are having vaginal sex. After this time period, you’ll receive the greatest PrEP effectiveness.

While PrEP is effective for preventing HIV without condoms, it does not protect against other sexually transmitted infections or diseases. If you have concerns about getting other STIs like chlamydia, HPV, or gonorrhea, you should wear condoms during sex. It’s generally recommended to use condoms with sexual partners with whom you’re unsure of their sexual history and sexual health. The risk of HIV and other STIs is lower with exclusive partners and those who you know do not have other infections.

How long is PrEP effective after stopping?

The levels of PrEP in the blood may be high enough to protect against HIV for a few days after stopping PrEP. Half of the drug concentration may be completely cleared from the body by day 7 after stopping treatment. 

PrEP is most effective when taken daily. It’s extremely important that you do not miss or skip a dose of PrEP. How effective is PrEP after you miss a dose? You may experience decreased PrEP effectiveness after missing or skipping a dose. If you miss a dose, take a dose as soon as you remember it. You might use an alarm or pillbox to help you remember to take your PrEP medication. 

If you find that you’re taking PrEP irregularly or you’re missing several doses in a row, you should consult your doctor for medical advice and guidance. If you don’t have sex regularly or you can predict when you will have sex, you may be a candidate for event-based PrEP.

Does PrEP stop transmission of HIV?

Yes, PrEP stops the transmission of HIV in at-risk individuals. However, PrEP needs to be taken every day in order to be the most effective for HIV protection. HIV that doesn’t respond to PrEP, or PrEP-resistant HIV, is rare and occurs if a person takes PrEP with an undiagnosed HIV infection. It’s important to get tested for HIV before starting PrEP for this reason.

If you’re looking for more information on PrEP, DeliverDose is here to answer your questions. You can buy PrEP at an affordable cost and get free shipping from DeliverDose. All medications are sourced from high-quality manufacturers to ensure you’re getting the most effective treatment. 

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