HIV Pre Exposure Prophylaxis (PrEP)

HIV Pre Exposure Prophylaxis (PrEP)

(Caring & Treating Since 2005)

What is HIV PrEP (Pre Exposure Prophylaxis)?

HIV PrEP is an extremely effective way of protecting yourself from HIV. It is currently one of the central pillars in our efforts to end the HIV epidemic in the world.

When someone is exposed to HIV through sex or injection drug use, PrEP can help stop the virus from establishing a permanent infection in the body.


HIV PrEP can be taken in several different ways depending on your unique lifestyle. The most common and effective way to take it is with a daily dose – a single tablet taken at around the same time every day. In medical studies, this has been shown to provide the best level of protection against HIV. Also, this schedule is easy to remember and adhere to, thereby reducing the chance of consuming the wrong amount of medication at the wrong time.

The medication currently recommended for HIV PrEP has also shown to be safe and effective for long-term use and rarely causes any significant side effects.

Because no prevention strategy for sexually active people is 100% effective, individuals taking PrEP are still encouraged to use other effective prevention strategies to maximally reduce their risk, including:
• Using condoms consistently and correctly
• Getting HIV and STD testing with partners
• Choosing less risky sexual behaviours, such as oral sex or mutual masturbation
• For people who inject drugs, getting into drug treatment programs and using sterile equipment

The more prevention options patients choose, the greater their protection. Some HIV prevention strategies, such as using condoms, can also provide protection against other STDs, which PrEP does not prevent.

Also Read: 7 FAQs on Pre Exposure Prophylaxis (PrEP)

Who can take HIV PrEP?

HIV PrEP is recommended for HIV-negative individuals who belong to a high-risk group for HIV infection.

HIV High-Risk Groups:

  • Someone who has an HIV-positive partner
  • Someone who has multiple sex partners, a partner with multiple partners, or a partner whose HIV status is unknown and does not practice safe sex
  • Someone who has sex with commercial sex workers
  • Someone who has recently had a sexually transmitted disease (STD)
  • Someone who injects drugs, or has unprotected sex with someone who injects drugs

How to Take HIV PrEP (Pre-Exposure Prophylaxis)?

1.) Daily PrEP

Daily PrEP Regimen: 

  • Lead in time 7 days.
  • Taken daily at the same time  +/- a few hours ok


  • Anal, Vaginal/Frontal sex


  • Can be taken anytime of the day with or without food
  • In the event a pill is missed, adequate protection is still conferred.

2.) On Demand PrEP (Event Based Dosing)

On-Demand PrEP Regimen: 

Planned condomless sex 24 hours in advance:

  • take 2 pills 2 – 24 hours before sex
  • take 1 pill on the day of sex
  • take 1 pill 24 hours later

If having sex for an extended period of time, perhaps over a few days or a weekend, continue to take a pill every 24 hours until you have 2 sex-free days.


  • Only for Anal sex
  • More studies required to show effectiveness in Vaginal/Frontal sex


  • This option is not recommended if you have an active hepatitis B infection. The drugs in PrEP also suppress the hepatitis B virus and so starting and stopping HIV PrEP can potentially cause viral flare-ups and liver inflammation.

Teleconsult & Medication Delivery

We are offering DTAP Teleconsult. This teleconsult service allows our current patients and new patients to connect with our doctors during clinic operating hours for non-emergency consults.

After assessment and consultation, we will also deliver your medications straight to your doorstep!

What is Event Based Dosing?

HIV PrEP is the so-called “Event Based PrEP.” This regimen is for people who have decided that they do not want to take HIV PrEP daily and only want to take it prior to an event.

The regimen requires the the individual to take 2 tablets of the HIV PrEP medicine between 2 to 24 hours prior to the event, followed by 1 tablet on the day of sexual intercourse, and a final tablet 1 day after after sex. Medical studies show that the protection provided against HIV for this regime is not as good as if the medicine is taken daily.

Furthermore, this regimen is more complex and therefore increases the risk of the individual taking the wrong amount of medication at the wrong time.

Descovy As New HIV Medication For HIV PrEP

Descovy (brand name) is a FDA approved new drug combination of tenofovir alafenamide (TAF) for use as HIV PrEP, which has shown to be equally effective in preventing HIV infection whilst touting an improved safety profile for renal and bone toxicity.

Descovy is currently available in all Dr Tan & Partners (DTAP clinics) in Singapore. It is a prescription only medication and must be prescribed by a doctor. Speak to our doctors for more information about Descovy and find out if a HIV-1 treatment that contains Descovy is right for you.

Frequently Asked Questions (FAQs) on HIV PrEP

HIV PrEP should not be mistaken for HIV PEP (HIV Post Exposure Prophylaxis).

HIV PEP is for any individual who is at risk of HIV infection AFTER an HIV exposure, and requires taking anti-HIV medications for a month to reduce his or her chances of HIV infection. This must be started within 72 hours of a potentially risky exposure.

HIV PrEP must be started BEFORE any exposure, in the ways outlined above.

Both HIV PrEP and HIV PEP do not 100% reduce your chances of HIV infection, nor prevent you from being infected with other Sexually Transmitted Diseases (STDs) besides HIV.

HIV PEP as an HIV prevention strategy was first developed for healthcare workers, who are being exposed to contaminated blood or needlestick injuries. It has since expanded to other HIV high-risk activities such as sexual exposure and intravenous drug use.

We do not recommend stopping condom use once you have started PrEP.  Combining HIV PrEP and consistent condom use give you greater protection against HIV infection.

Also, HIV PrEP does not prevent you from other STD infections. Condom use can help prevent other STDs like syphilis, gonorrhea, and chlamydia.

Is a combination of anti-HIV medications. This was first approved for treatment of HIV infection in 2004, and was subsequently approved for use as regular PrEP in 2012. There have been some studies evaluating other drugs, but so far they have not shown the same effectiveness and tolerability.

Like any drugs, HIV PrEP can have some potential side effects.

A small number of people will experiences “start-up syndrome” like:

  • Gastrointestinal discomfort
  • Dizziness
  • Bloating nausea
  • Weight Loss

HIV PrEP may have a small risk of affecting your kidney and bone function. Hence, regular visits every 3 months with our doctors are essential to monitor for any complications.

You can stop HIV PrEP at four weeks after you have had any high-risk HIV exposure, which should be followed by an HIV test and potentially other STD testing.

Speak To Our Doctor Today!

HIV PrEP should not be seen as the magic pill that provides a magic shield against HIV. It is just one more effective tool we have to reduce the risk of HIV infection.

Furthermore, HIV PrEP does not protect the user against other STDs. Therefore, even if you are on HIV PrEP, it is important to still to use a condom regularly, as well as get your regular STD screening & HIV Testing.

The HIV Pro-Viral DNA test can be used in specific situations where there are challenges to getting an accurate HIV diagnosis with other available HIV tests including HIV Antibody tests (3rd Generation HIV test), HIV Antibody and Antigen tests (4th Generation HIV test) as well as HIV RNA PCR test.

If you are interested to find out more about HIV PrEPplease call our any of our clinics or drop us an email at for an appointment with our doctors.

Related Articles on HIV

Get the latest news and articles by our doctors

Our Branches
Health Info
Our Doctors

Request An Appointment

Speak to our doctors about your medical concerns today.

  Proudly Supporting:

Proudly Supporting:

© Copyright 2005 – 2022 Dr. Tan & Partners. All Rights Reserved.