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!

Medicines to Prevent HIV – PEP and PrEP

PEP which is short for Post-Exposure Prophylaxis is a well studied method of preventing HIV infection after a person has been exposed to HIV.

This is based on the theory that if HIV replication can be inhibited as early as possible after the virus enters the body, it can prevent a permanent infection. This was first developed for healthcare workers such as doctors and nurses who would inadvertently poke themselves with an infected needle. It has since been expanded to treat people who got exposed to HIV in any other way; sexually, intravenous drug use etc

Click here for PEP details including prices.

PrEP which is short for Pre-Exposure Prophylaxis is taking medicines to ‘vaccinate’ yourself against HIV.

Now, another method is fast catching the interest of scientists and doctors worldwide. This is known as HIV PrEP which is short for Pre-Exposure Prophylaxis. As the name suggests, this involves a patient taking an anti-HIV medication everyday regardless of whether he or she has been exposed to HIV or not. This is so that if the HIV virus does enter the body, the virus will be immediately prevented from replicating and thus preventing the infection from becoming established and thereby incurable.

Learn more about HIV PrEP event-driven based strategy 

A Fact Sheet published by the US CDC in June this year detailed medical trials conducted in Thailand, Botswana and the United States which involved intravenous drug users, heterosexual men and women and MSM (men who have sex with men)1.

Click here for detailed information on PrEP

A Press Release by NIH2 published on 23rd November 2010 stated that their study titled ‘Chemoprophylaxis for HIV Prevention in Men’ found that taking an anti-HIV drug everyday reduced the risk of HIV infection among MSM and bisexual men by 43.8%. This number was even higher at 72.8% if the patients followed their doctor’s instructions and took the drug at least 90% of the time.

Dr. Anthony S. Fauci M.D. who is the Director of NIAID pointed out that ‘No single HIV prevention strategy is going to be effective for everyone’. He went on to elaborate that more research has to be done for women and heterosexual men with regards to the effectiveness of PrEP.

The concept of PrEP might seem confusing to some of us who might wonder why some people would knowingly put themselves at risk of HIV and therefore see the need to take a preventive medicine everyday.

I like to compare this to a race car driver who straps himself into a virtually inescapable cockpit next to an engine exploding at 6000 times per second sitting next to a tank of highly combustible fuel. Then he wears a helmet and fire-retardant clothes.

Early, Fast and Accurate Anonymous HIV test – Click Here

I feel its all about a lifestyle choice and the risk we are willing to take for that lifestyle. And of course, science has developed ways for us to manage this risk be it high-tech flame retardant clothes or anti-HIV medication.


1. Centers for Disease Control and Prevention – CDC Trials of Pre-Exposure Prophylaxis for HIV prevention
2. National Institute of Allergy and Infectious Diseases – Daily Dose of HIV Drug Reduces Risk of HIV Infection

Click here for HIV Testing FAQ
Click here to see the full range of our HIV/STD Services


Need more advice?

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

Singapore Branches


Where to find us – here

Selected clinics are open on Saturday and Sunday.

Email: hello@dtapclinic.com.sg

All Our Doctors are Fully Certified and Trained to conduct specialised STD Screening,  STD Testing & STD Treatment and HIV Testing.

For lady patients who prefer female doctors, we have professional certified female Doctors to attend to your medical needs.


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

If you have any questions, visit our free online forum on sexual health, HIV and STDs.

More on HIV symptoms.

If you need a HIV test visit Our Clinics anytime during our opening hours. You do not need an appointment.

Find out more about Anonymous HIV testing at our clinics.

Can’t wait for 3 months to find out? Find out more about Anonymous Rapid HIV Combo test at our clinics.

If you had a high risk exposure to HIV within the past 72 hours, you can take medicines to reduce your risk of actually contracting HIV. Find out more on HIV PEP Treatment.

Other Articles:
HIV CMIA Test Accuracy
Getting HIV from Oral Sex
More on HIV symptoms
How long can HIV live outside the body?
Erectile Dysfunction
Premature Ejaculation
Testosterone Deficiency Syndrome / Andropause

About Dr. Tan
Dr. Tan graduated from the National University of Singapore in 2001. His residency was in the two largest public hospitals in Singapore; Tan Tock Seng Hospital and Singapore General Hospital.

Find the profiles of our panel of doctors.


  1. nameless

    Dear dr. tan

    I am on pep treatment now after 13 hour of exposure. Can i ask how high is the rate of been not infected with hiv?


  2. Hi dr tan. My bf is hiv possitive but we had sex for many time. But he’s taking he’s antiretroviral. I do test my self also. But its negative. Do u think i need a second opinion. Or should i take prep.

    • The fact that your BF is on anti-retrovirals reduces the chance of him passing HIV to you considerably. As high as 90%. The risk of you catching HIV from him via unprotected vaginal sex is about 1%. If you use condoms this is even lower. So I am not surprised that you have not been infected with HIV as yet. I personally know of sero-discordant couples who have been together for years without the HIV -ve partner getting infected with HIV. That said, the fact is should you choose to have sex with your BF, there is always a chance that you are infected with HIV (although we have established the fact that this chance is low). If you start on PrEP, you can lower this (already low) chance by as much as 99%. You can decide yourself if you think this is worth it or not.

  3. Hi dr tan .I have a bf from sg. Hes hiv carrier . I having sex with him in manytimes without condom.biy he’s antiretroviral.but after tree months i get tested my self. For hiv. But its negative.do u think i j
    Have to test again in to the dr. As second opinion

  4. Does your clinic provide PrEP treatment? if yes, what is the estimated cost? Does PrEP treatment really help to prevent HIV infection?

    • Yes we provide Truvada. There have been many studies to document the effectiveness of PrEP and it is recommended by the US FDA. Truvada costs $900 for 30 tablets (1 month).

      • I’m keen to get the Truvada PrEP. how do i go about getting it from ur clinic?

        • You can come down anytime without an appointment. Get registered. Speak to the doctor and we will advice you accordingly. We will then dispense the medicine from the clinic.

  5. Capricorn


    I had a massage and after that handjob. But I have touched my penis shaft with her fluid for second only and immediately I wiped my hand and penis also.

    Does I required PEP or not. Any chances of HIV

    • This forum is not for medical consultations. I cannot tell you if you need PEP or not. Please see your doctor.

  6. Hi dr
    Does receving oral sex from someone will be exposed to hiv?
    How do i confirm it is negative if it just happened 4 days ago. Thank you.

  7. Worry

    Hi Doc,

    Will pep affect the window period..

    I had been tested negative at 5 month after exposure.. Is it conclusive?

  8. Worry

    Will pep affect the window period?

  9. Hi Dr. Tan,

    Do you know where can i have HIV Combo test in KL?

  10. suan lin

    Dear Dr. Tan,
    I tested negative at 2 months. Then at 4 months I saw a doctor who asked me to take a few tests. I tested positive for syphillis. But the lab doctor said the screening procedures they used for hiv were that if anyone tested within a 30 minute range and showed signs of positivity then they gave him or her a positive result. I however, showed signs post the 30 minutes range. Therefore, since the test had validity only and only within 30 minutes I was given a negative but my doctor asked me to do a western blot. my western blot at 5 months gave all negatives. Keeping this into mind, and the fact that syphillis could have showed a few syptoms post the 30 mins for the hiv test, and also the fact that I was given a negative in all 3 tests at 2, 4 and 5 months, do you think I should go in for any other test. I can’t seem to put this episode to rest. Hoping you won’t ask me to do the tests again. Thanks for all your help.

    • Hi suan lin,

      So all this worry is from a positive HIV test that was read AFTER the 30 min limit? Oh dear. That was really quite unnecessary. Interpretation time limits are set on tests for a very good reason: they cannot be read with any kind of accuracy or reliablity outside these limits. You do not have HIV, please do not test anymore.


      Dr Tan

  11. suan lin

    Dr Tan,
    Would a western blot at 5 months be accurate?

    • Hi suan lin,

      A Western Blot is not a HIV screening test and should not be used as such. The result of a Western Blot has to be interpreted in the setting of a positive screening test.


      Dr Tan

  12. Confused

    Dear Dr Tan,

    Today I have a protected virginal sex after getting message from a lady. I’m worried she might be a HIV or STD carrier. I really regret my action and heard that PEP can prevent HIV within 76 hrs of exposure. Would you advise me whether I should get PEP?

    • Confused

      typo error… i mean massage and not message

    • Hi Confused,

      The risk of contracting HIV via protected vaginal sex is very near zero. Condoms are also protective against a male catching Gonorrhea. However, condoms are not that effective against other STDs like Chlamydia, NSU, Syphilis, Herpes etc. In summary 1. You are NOT a candidate for PEP because of your extremely low risk of HIV 2. You should get screened for the other STDs.


      Dr Tan

  13. Dear Dr. Tan,

    May I know how could I obtain the PEP? As I am worried after having an one-night stand with a friend, whom I hardly know, and the condom broke inside me. We got the condom replaced, but his fluid may still infect me if he is a carrier of any STD or even HIV. I have not been active in sex for close to a year, and I am not having menses so the chances of my having vaginal damage during the intercourse was low. I am just hoping that decreases my risks of HIV infection. I am still within 72 hrs of possible infection, I am really worried and would like to get your help. I know this sounds paranoid, but the ONS really affected me a lot and distracts me from work. I wish I have never had it.



    • Hi Lucy,

      This requires a discussion on your potential risk and weighing that against the potential side effects of PEP. Also, we need to discuss the management for other potenial STDs. You can see me at my clinic at Robertson Walk anytime today before 8pm.


      Dr Tan


  1. Most Popular HIV Articles | HIV - [...] Medicines to Prevent HIV – PEP and PrEP [...]
  2. Tablets to prevent HIV – PrEP | HIV Test in Asia - [...] 2010, I wrote a blog article on PrEP which is short for Pre-Exposure [...]