AIDS Concern has prepared this fact sheet to provide the community with basic knowledge on PrEP to make informed decisions about sexual health. Please note that the information below is not intended to give medical advice to individuals who are interested in taking PrEP. AIDS Concern encourages interested individuals to consult their doctors for advice directly.


AIDS Concern supports a combination of strategies to HIV prevention (using a variety of approaches). PrEP is one effective addition to a whole range of HIV prevention tools but not a substitute for condom use.


Please note that at the current time access to PrEP in Hong Kong is not provided through the public health system. Later in the information sheet you can find information about accessing PrEP through a private doctor or by going to the Thai Red Cross.


Q: What is PrEP?

A: ‘PrEP’ stands for Pre-Exposure Prophylaxis, an anti-HIV medication programme that can help stop HIV-negative people from getting infected by HIV even if being exposed to HIV. Using the drugs Truvada (tenofovir and emtricitabine formulate) as its components, the medicine can prevent HIV from making new virus as it enters the body and keep the virus from establishing a permanent infection. Please note that PrEP is NOT a vaccine that produces HIV antibody in the body, and it needs to be used consistently over time to reduce the risk of acquiring HIV. Taking one pill before high risk sex will not protect you.


Q: Is PrEP effective in preventing HIV?

A: Yes if used properly. PrEP is proved to be effective in reducing the risk of acquiring HIV through sex when used consistently with strict adherence. According to the iPrEx clinical study by the US Department of Health and Human Services in 2011, the risk of HIV acquisition was reduced by 96%-99% among men who have sex with men (MSM) who adhered well to PrEP. Studies show that daily doses of PrEP also reduced HIV transmission among heterosexual serodiscordant couples (in which one partner is infected with HIV and the other is not) by 75%.


Please note that the effectiveness of PrEP is highly contingent on the degree of drug adherence of the user. One needs to adhere strictly to the drug regimen to reduce the risk of acquiring HIV.


AIDS Concern is advocating for PrEP to become available in Hong Kong for people at high risk of HIV and in particular for demonstration projects in Hong Kong. Please click here for AIDS Concern’s advocacy position.


Q: Am I suitable for this medication? Do I need to use condoms as well?

A: The USA Centre for Disease Control and Prevention (CDC) and World Health Organization (WHO) recommend PrEP for people who are HIV-negative and at substantial risk for HIV infection. The World Health Organisation recommends that PrEP should be one additional option for HIV prevention, but did not recommend it to be a substitute for condoms. Although PrEP is already highly effective in preventing HIV infections, there are by far a few reported cases where people who adhere to PrEP have become HIV positive. It should be noted that PrEP is a biomedical intervention measure, and it may have limitations in preventing HIV-virus that are already resistant to Truvada. Therefore, people using PrEP should also continue using condoms when having sex to ensure low risk of HIV and also other sexually-transmitted diseases. People who take PrEP should also have HIV and STI testing every 3 months and receive close monitoring of their medication adherence and risk behaviors regularly.


Q: Does PrEP have side-effects?

A: Side effects vary from person to person. Short term side-effects include headaches, weight loss, diarrhoea, nausea, and fatigue. Long-term side effects such as kidney dysfunction and decreased bone mineral density do affect a very small proportion of PrEP users. This is why medical supervision and follow up tests are important.


In PrEP studies, use of tenofovir has been associated with small decreases in key measures of kidney function (creatinine clearance and glomerular filtration rate, GFR) and 0.4-1.5% loss in bone mineral density, affecting up to 2% of participants. However, most of their renal function and bone mineral density was also found to have returned to the baseline level after withdrawing PrEP use.


PrEP users are advised to have their health conditions continuously monitored when taking PrEP, and consult their doctors when necessary.


Q: Is there a possibility of developing drug resistance?

A: As Truvada is also commonly used in antiretroviral treatment for HIV positive people, some people are worried that PrEP users would develop drug resistance to Truvada which could make HIV treatment ineffective if they become HIV-positive in the future. Among the 9222 users who have taken on PrEP in trials, only 11 people developed FTC or TDF-resistant HIV infection (n=0.1%), and it occurred mainly among people who were already acutely infected with HIV before initiating PrEP. In other words, if PrEP users do not adhere well to the drug regimen and engage in high risk behavior at the same time, unrecognized and acute HIV infection would expose them to the risk of developing drug resistance when they continue on taking PrEP. In order to avoid the risk of developing drug resistance, PrEP users should adhere strictly to the drug regimen suggested by the doctor, and have initial and regular HIV testing to be consistently aware of their HIV status.


Q: How can I use PrEP to effectively prevent HIV?

A: There are currently 2 dosing regimens proved to be effective in preventing HIV.


Please note that only taking one pill before sex wouldn’t protect you from HIV. It takes time for the different body parts to build up the drug concentration. We suggest potential PrEP users consult a doctor directly to choose the regimen most suitable for them. Also, if you encounter any problems adhering to the drug regimen, please consult your doctor directly.



Daily dosing factors to consider

Event-driven dosing factors to consider

People who might be suitable

  • People who don’t want to have planned sex
  • People who cannot request their partner to have planned sex

People who have frequent sex

  • People who are sure they will have planned sex
  • People who can require their partner to have planned sex
  • People who don’t frequently have sex


  • Drug regimen is easier to follow and the possibility of missing a dose is lower
  • Protective efficacy will not fluctuate too much even if you miss a pill occasionally
  • Can freely choose when to take the pill every day


  • Use fewer drugs and lower the possibility of developing side-effects
  • Lower financial burden

Things to consider

  • Higher financial burden


  • Planning of sex is needed
  • Regimen is relatively hard to follow, and missing one pill would significantly reduce the protective efficacy



Q: Is PrEP available in Hong Kong?

A: PrEP is not yet available in the public health system in Hong Kong. Some private doctors are prescribing but the cost is quite high, which is priced at approximately $8000 to $10000 a month. If you want to get PrEP privately please contact AIDS Concern by telephoning 2898 4411 so that we can advise you on possible clinics.

AIDS Concern is advocating for PrEP to become available through the public health system. Other options are to access PrEP by visiting the Red Cross clinic in Bangkok. However, we strongly recommend you read the information about these options later in this information sheet before considering either of those options. Getting medication like PrEP without medical supervision can be dangerous for your health.


Q: Some people are going to Thailand to get PrEP. Is this a good idea?
A: There are a number of providers in Thailand advertising PrEP. However, if you want to access PrEP it is important that you do so from a legitimate supplier where you get the necessary medical checks to ensure that you are safe to take the medication. One reputable supplier is the Thai Red Cross Research Centre which has a Prep-30 project. This does require you to go to Bangkok.


Please see the link here if you would like to learn more: 


It should be noted that the importation of pharmaceutical products and medicine are controlled under the Import and Export Ordinance (Cap. 60), thus must be covered by a license issued by Department of Health under delegated authority of the Director-General of Trade and Industry Department. Pharmaceutical products and medicines imported in the personal baggage of a person entering Hong Kong and which are accompanied by him and in a reasonable quantity for his personal use may be exempted from licensing requirement. People who are going overseas to get access to PrEP are therefore strongly advised to keep a medical certificate provided by the prescribing doctor with themselves when they have to bring PrEP to Hong Kong for personal use. 


You may call the Drug Office of Department of Health (Tel.: 2319 8460) for enquiries relating to import/export of pharmaceutical products and medicine or Customs and Excise Department (Tel.: 2815 7711) for general enquiry on Customs clearance.

Q: I would like to buy PrEP from the internet. Is this a good idea?


A: Buying medication over the internet is a bad idea unless you can be sure that the supplier is legitimate. Otherwise there is a risk that you may be given fake pills that do not work or which cause you harm. It is also important that anyone being prescribed PrEP has medical supervision for this to happen. 


Q: I’ve decided to take PrEP. What do I need to pay heed to?

A: If you do decide to take PrEP, please remember these 3 crucial factors:
– When you start using PrEP, you must absolutely be sure that you do not have HIV to avoid the risk of drug resistance. Get tested at AIDS Concern or Social Hygiene Clinic for free. You may also go to a private clinic for testing; 
– Have your blood checked first to ensure that your kidney and liver functions are alright; and
– Get tested every 3 months for HIV and other STIs, and have your kidney and liver functions regularly monitored through your doctor.