HIV Pre-Exposure Prophylaxis – PrEP

Pre-Exposure Prophylaxis

HIV Pre-Exposure Prophylaxis – (PrEP)

In 2010, I wrote a blog article on PrEP which is short for Pre-Exposure Prophylaxis.

Since then, there has been many updates and new research published so it is high time for an updated entry.

Just to recap, HIV PrEP is a medicine that a person takes everyday which reduces his/her risk of contracting HIV. This is not a new concept in medicine. Take for example tablets taken daily to prevent Malaria or tablets taken daily to prevent pregnancy.

This should not be mistaken for PEP which is Post Exposure Prophylaxis. PEP are medicines taken AFTER a person has been potentially infected with HIV.

So what exactly is PrEP?

PrEP is simply a tablet taken daily that reduces a person’s risk of contracting HIV.  It’s that simple. The tablet most studied for use as PrEP contains 2 medicines:  tenofovir disoproxil fumarate 300 mg (TDF) and emtricitabine 200 mg (FTC). This is marketed under the brand name Truvada and is made by a company called Gilead Sciences.

Descovy as new medication for HIV PrEP

Descovy (brand name) is a FDA approved new drug combination of tenofovir alafenamide (TAF) + emtricitabine 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.

How effective is PrEP?

There have been many studies with varying results. Generally, protection rates differ between groups with different sexual orientations. Numbers range from 50% to 84% according to the 4 studies quoted in the US CDC’s Interim Guidelines. Other publications quote protection rates as high as 99%.

We must bear in mind that like every other method of HIV prevention, PrEP is not failsafe. It is one of the many weapons in our current arsenal to reduce the burden of HIV on the world. Other prevention methods include:

  1. Consistent and correct condom use.
  2. Access to treatment. Treatment as prevention.
  3. Education.
  4. Male circumcision.

What are the side effects of PrEP?

Minor side effects such as nausea, headache and weight loss are possible.

Major side effects like effects on the kidney and bone density are rare.

In my personal experience prescribing HIV PrEP, I have not come across anything more than some minor nausea.

How can I start PrEP?

Come see us at our clinic. You will need several tests including a HIV test, STD screening and a kidney function test.

You can start on the pills immediately. It is best to be on the pills for at least 7 days before engaging in any risky encounters.

How can I stop PrEP?

It is best to continue PrEP for at least 4 weeks from the last risky encounter.

You will also be advised to get screening tests done for HIV and other STDs 3 months from the last encounter.

How long can I take PrEP for?

PrEP can be taken indefinitely and should be taken as long as you remain at risk of HIV.

It is best to see your doctor every 3 months to screen for HIV and STDs and monitor for potential side effects.

For further reading:

My PrEP Experience Blog is a great resource on everything you need to know about PrEP.

It also contains real life stories from patients who have taken PrEP and their experiences. I highly recommend that you check it out if you are considering starting on PrEP.

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.


1.) Dr. Tan and Partners (DTAP Clinic) @Siglap

Men’s Health & Sexual Health Clinic

Dr. Edwin Ong is currently practising in Men’s Health & Sexual Clinic @Siglap 

914 East Coast Road
#01-04 The Domain,
Singapore 459108

+65 6962 2144

2.) Dr. Tan and Partners (DTAP Clinic) @Somerset

Men’s Lifestyle Clinic

Dr. Taufiq is currently practising in Men’s Lifestyle Clinic @Somerset (Orchard Building) 

Orchard Building
#10-08, 1 Grange Road
Singapore 239693

+65 6262 0762

3) Dr. Tan and Partners (DTAP Clinic) @Raffles Place

Men’s Health & Sexual Health Clinic

Dr. Benjamin Loh is currently practising in Men’s Health & Sexual Clinic @Raffles Place

20 Cecil Street,
#02-01 PLUS
Singapore 049705

+65 6962 7144

4) Dr. Tan and Partners (DTAP Clinic) @Holland V

Men’s Health & Sexual Health Clinic

Dr. Julian Hong is currently practising in Men’s Health & Sexual Clinic @Holland V 

15B Lorong Liput
(Next to Holland Piazza)
Singapore 277730

+65 6235 1339

5) Dr. Tan and Partners (DTAP Clinic) @Novena

Men’s Health & Sexual Health Clinic

Dr. Julian Ng is currently practising in Men’s Health & Sexual Clinic @Novena Medical Centre

Novena Medial Centre
#08-31, 10 Sinaran Drive
Singapore 307506

+65 6397 2095

mens Forum