Summary
PrEP is a safe, easy to use medication that significantly prevents against HIV. It is recommended by reliable health organisations such as the World Health Organisation and the Center for Disease Control to be a safe and effective management tool in the fight against HIV transmission.
This fact sheet aims to clarify misconceptions and confusion about the use of PrEP and give further information for people who may be contemplating using it. PrEP is becoming more and more popular every year.
Pre-Exposure Prophylaxis, PrEP, is a once daily medication taken to prevent the transmission of HIV. It should be used by anybody at risk of HIV transmission. It is recommended for most sexually active Men who have sex with Men not in monogamous relationships. Heterosexual people may use it if they are engaging in sexual liaisons and want to prevent HIV anyway.
What is PrEP?
Pre-exposure Prophylaxis is a once per day combined antiviral tablet that can be taken to prevent the acquisition of HIV. Studies have shown that it is very effective and still effective if a dose is missed. The exact efficacy of this medication is unknown with results varying among studies however where the tablet is taken reliably every day it is >85% effective in preventing HIV and perhaps higher. This medication has been shown to work for penile-vaginal and male-male intercourse.
Who should have PrEP?
Center for Disease Control guidelines suggest PrEP for anybody at substantial risk of HIV. This may include:
- Men who have sex with men
- Somebody who is having sex outside of one relationship with unknown partners
In general, high risk sexual activity for HIV should prompt a discussion about PrEP.
How is it taken?
PrEP is a combined antiviral medication that is taken once per day.
What monitoring and follow up is required?
Before PreP and Every 3 months: HIV test, full STD test, liver and kidneys.
Before PrEP is started, it is essential to test for HIV. The reason for this is that PrEP cannot treat HIV virus completely and risks causing a ‘resistant infection’; meaning that the HIV infection may not be treated by standard medications.
There are a few ways to test HIV:
- Early detection blood test; this uses nucleic acid or bits of DNA. HIV is detectable this way 10-33 days after exposure.
- Antibody or Antigen tests; this test uses your immune system to check for HIV. the p24 antigen test can detect HIV between 18-45 days after exposure whilst traditionally antibody tests are useful after 90 days from exposure
What STDs should men who have sex with men check and how often?
Men who have sex with men have a higher chance of an STD. Not all STDs have symptoms and many will go undetected for a long time, increasing the chance of passing them on. Some STDs make it more likely to get other STDs (for example syphilis and HIV) and so regular testing and treatment is recommended as a total strategy for HIV prevention.
It should also be noted that 30% of women who become HIV positive are estimated to gain HIV from bisexual partners and ⅓ of women engage in anal sex; as such rectal swabs may be recommended for women who have sex with a bisexual partner. These matters can be discussed with your doctor.
The following chart gives an idea of the tests a person should have on a regular basis to screen for STDs.
For Men who have sex with Men:
| Site | Tests | Additional | How Often |
| Rectum | Chlamydia and Gonorrhoea |
+/- herpes if needed +/- anal ‘PAP’ smear |
Every 3 months |
| Oral | Gonorrhoea |
+/- herpes if needed +/- anal ‘PAP’ smear |
Every 3 months |
| Urethra (penis) | Chlamydia and Gonorrhoea |
Mycoplasma and ureaplasma if symptoms +/- herpes if needed +/- anal ‘PAP’ smear |
Every 3 months |
| Blood | Syphilis, HIV, Hep C |
• Hep B if not vaccinated +/- herpes if needed +/- anal ‘PAP’ smear |
Every 3 months |
What Medication do I need to get for effective PrEP?
One such medication approved by the FDA (Food and Drug Administration in the USA) for the prevention of HIV and that is the combination of Tenofovir/Emtricitabine 300mg/200mg combined once daily tablet. This formulation may have different forms; or in your local area a different variant of this class of medications may be more available.
Do I have to take the tablet every day or is on demand effective?
The official recommendation of major health bodies such as the Center for Disease Control is to recommend daily dosing. Daily dosing is achieved more reliably by people taking PrEP than condom use. On demand dosing involves taking 2 tablets 2-24 hours before sexual activity, 1 pill 24 hours after sexual activity and 2 pills 48 hours after sexual activity. It is reported to have high efficacy (>80%) but further studies are needed. In general, it is better to take it regularly but on demand is better than nothing.
Does PrEP mean I don’t have to use condoms?
Not at all. Unfortunately, PrEP only prevents HIV and does change the risk of other diseases such as gonorrhoea, syphilis, herpes, chlamydia to name a few. Condom use is still essential to manage other diseases.
What other medications will interact with this?
Some antiviral medications such as aciclovir or ganciclovir can interact with this medication so let your doctor know all the medications you are on before starting it. If you are on other antiretroviral medications, please inform your doctor.
How long does it take to work?
Nobody really knows how long PrEP takes to work; it takes 20 days for blood concentrates to remain steady and condoms are recommended until this time.
What are the side effects of PrEP?
You may read that there is a small loss of bone density in some people on PrEP. This loss is quite small and there is no association with fractures or fragility. Some patients experience nausea but very few other serious side effects have been reported.
What about breastfeeding and pregnancy?
Data is limited on these topics and should be discussed on a case by case basis.
What do I do if I have HIV?
If you become positive on HIV, do not panic and come to see your doctor. The next steps are to perform CD4 counts, total viral load, find out more about the genetic ‘type’ of the HIV to guide treatment and then start a treatment regimen. Put bluntly, if you take the tablets and your viral load is undetectable, you have a normal life span and will not pass on HIV.
How can I obtain PreP?
PreP is best obtained by seeing a doctor or a specialist sexual health clinic in your locality. Some parts of the world, such as clinics in Thailand, have historically been able to post the medication abroad. However, this is up to each individual provider.
References
Clinical Practice Guidelines on HIV prevention:
Centers for Disease Control and Prevention: US Public Health Service: Preexposure prophylaxis for the prevention of HIV infection in the United States—2017 Update: a clinical practice guideline. https://www.cdc.gov/hiv/pdf/risk/prep/cdc-hiv-prep guidelines-2017.pdf. Published March 2018
CDC Guidelines and further reading on STD testing recommendations for men who have sex with men:
https://www.cdc.gov/std/life-stages-populations/stdfact-msm.htm
