Dr. Tan and Partners is one of the few approved Anonymous HIV Testing Centres in Singapore. A detailed write up on our service is available here.

Other STD services: Early STD Screening, Rapid Hepatitis B Blood Test, Swab for Gonorrhea and many more... contact us to make an appointment now!

HIV Prevention: To HIV PrEP or not to HIV PrEP?

If you’re reading this, most probably you would have an awareness about HIV and are worried about getting infected. Rightfully so, as there is still no cure for HIV and it can lead to a severe disease called AIDS and eventually death.


Every year more than 400 new cases of HIV are reported in Singapore majority of which are still in the prime of their lives between the ages of 20-49. So if you are HIV negative and sexually active, you have a right to be afraid of HIV infection. So what do we have to protect ourselves from this deadly virus? Well the condom helps to reduce HIV transmission, STDs and pregnancy very well.


What if you are not able to use the condom? Or not keen to use the condom? Or worried about condom mishaps? This is where PrEP comes in.

Learn more: “A Quick Breakdown on How HIV Can be Transmitted



How effective are Condoms, Diaphragms and Circumcision in preventing HIV transmission?

What is PrEP?

PrEP stands for Pre- Exposure Prohylaxis. Prophylaxis means prevention. HIV PrEP involves taking one pill a day to prevent HIV infection.


How effective is PrEP?

It is effective in preventing HIV transmission up to 99%


How does it work?

PrEP prevents HIV from infecting your cells and multiplying. So if you do get exposed to the HIV virus, you will not get infected.


Do I need to take it daily?

For the PrEP to be effective, it needs to be taken daily. For men it will be take 7 days before its effective. For women it will take 3 weeks for it to be effective.


What is the difference between PrEP and PEP?

PrEP is pre exposure. HIV Post Exposure Prophylaxis is post exposure. PrEP is to be taken before you are exposed. PEP is taken only after you are exposed to a potentially high risk sexual encounter. PrEP is one pill to be taken daily. PEP is made up of 2 pills taken for a month. PEP has lower protection rate than PrEP.


HIV PEP treatment at our clinic


Condom Broke

Am I suitable for PrEP?


You are a suitable for PrEP if you are any of the following:


You are a gay/bisexual man and

  • have an HIV-positive partner.
  • have multiple partners, a partner with multiple partners, or a partner whose HIV status is unknown –and– you also
  • have anal sex without a condom, or
  • recently had a sexually transmitted disease (STD).


You are a heterosexual and

  • have an HIV-positive partner.
  • have multiple partners, a partner with multiple partners, or a partner whose HIV status is unknown –and–you also don’t always use a condom for sex with people who inject drugs, or don’t always use a condom for sex with bisexual men.


You inject drugs and

  • share needles or equipment to inject drugs.
  • recently went to a drug treatment program.
  • are at risk for getting HIV from sex.


Are there any side effects?

Like any drugs, PrEP does have side effects.  In a small number of people there is some gastrointestinal discomfort (e.g. gas, bloating nausea) or dizziness when starting PrEP.  For those who do experience discomfort it nearly always goes away after about a month. There is also concern that PrEP may affect your kidney or bone function. You doctor will monitor your bloods regulrly to check for this.


Do I still need to use condoms?

Taking PrEP and using condoms will further increase your protection rate from HIV. Taking PrEP is protective enough against HIV. However, you are still at risk for other STDs. For women, you still can get pregnant. Also a periodic STD and HIV Testing is needed to to check on your STD and HIV stats.


What if still have questions?

Call or email us to make an appointment with any of our clinics. Speak to the doctor to discuss if PrEP is really suitable for you.



If you are interested in getting HIV Pre-exposure prophylaxis (or HIV PrEP) or learning more, please visit Our Clinics.

All Our Doctors are Fully Certified and Trained to conduct specialised STD and HIV Testing.



Need more advice?

Come down to Our Clinics for a discussion with Our Doctors, or call our clinics for more information:

1.) Robertson Walk  (+65 6238 7810)

2.) Bencoolen Street (+65 6884 4119)

3.) Novena Medical Centre (+65 6397 2095)

4.) Scotts Medical Centre (+65 6694 2348)

5.) Somerset – Orchard Building (+65 6262 0762)

6.) Katong – East Coast Road (+65 6635 2551)

Where to find us – here

Click Here for Contact Details, Address and Opening Times.

Feel free to email your queries, feedback and suggestions on what other topics you want to see in the comments section below.


  1. Hello Doctor,
    I am on PREP for the past 2 months. I have not missed my doses.
    On one day I have missed Prep completely. On 5th march I missed Prep. On the next day 6th March I had Unprotected sex. Also on that day I have started as usual taking of Prep.

    My questions:

    1. Does prep is Effective irrespective of One missed tablet where verh next day Unprotected sex has happend.

    2. I am planning to stop Prep and to get into long term relatoonship.
    After the last exposure how many days I have to take Prep to be effectively prevent from Hiv.

    3. When can I test for HIV from my last exposure.

    Thanks Doctor.

    • PrEP is most effective when taken consistently (daily). Missing a dose will increase the risk of PrEP failure, although to what degree we cannot tell you. I would suggest completing another 28 days of PrEP post-exposure and then testing then. If you are more concerned, you may even consider adding Isentress for the 28 days if you are able to start it within 72 hours of exposure (essentially take PEP or post-exposure prophylaxis instead). If you are within that 72 hours and are keen for PEP, please visit us for a proper consult and evaluation.

  2. I just realized I asked Dr. Tan a question about a blogpost on PrEP by Dr. Taufiq. Please consider my question on the benefits of daily vs nondaily use of PrEP to be directed at you both 🙂 Thank you very much!
    Respectfully yours,
    Fred (I work for a medical company that distributes PrEP)

  3. Dear Dr. Tan,

    Doing some research on nondaily use of PrEP, i found your blogpost of March 2015 at the MyPrepexperience blog. In it, you describe how some of your patients are on a nondaily regime. The post strongly suggests you see nondaily PrEP use as effective.
    In this post of 2017 however, you clearly stress daily use. Is there a reason for this apparent change of mind, or should the above be read as an endorsement of a daily regime over a nondaily one? If so, in your opinion based on your experience with nondaily use patients, are there any obvious benefits of daily PrEP use over nondaily use? Thank you!
    Respectfully yours,

    • Daily PrEP offers greater protection (92-98% risk reduction), but for people who do not have frequent exposures, this can be a little costly. The non-daily regimen is called EBD, or event based dosing – this option offers about 80-85% risk reduction so it is still very effective.

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