PrEP – What You Need To Know

What is PrEP?

PrEP is a course of HIV drugs taken by HIV negative people before and after sex to reduce the chance of getting HIV.


Results in trials have been very successful, with PrEP significantly lowering the risk of becoming HIV positive and without major side effects.


The medication used for PrEP is a tablet which contains tenofovir and emtricitabine (sometimes known as Truvada).

How does PrEP work?

Taking PrEP before and after being exposed to HIV means there is enough drug inside you to block HIV if it gets into your body – before it has the chance to infect you.

How often do you take it?

PrEP is licensed for daily use but studies have shown that it can be effective when taken episodically.

The two ways to take PrEP are:

  • taken regularly (one tablet per day)
  • only taken when needed (two tablets 2 hours before sex, one tablet 24 hours after sex and a further tablet 48 hours after sex). This is often called ‘on-demand’ or ‘event based’ dosing.


Both methods have been shown to be effective. If PrEP becomes available in Ireland it is likely that both approaches will be used, depending on what is most suitable.

Who could take PrEP?

People who are at high risk of getting HIV. This includes gay and bisexual men, ethnic minorities, trans people and those in a relationship with an HIV positive partner who is not on successful treatment.


Other factors are related to a higher risk of HIV. These include:

  • A recent STI (especially rectal infection or syphilis).
  • Recent use of PEP (post-exposure prophylaxis).
  • Using some recreational drugs sex (crystal meth, mephedrone or GHB) – also known as Chemsex drugs.


Any of these mean you are likely to benefit even more from taking PrEP.

Where do I get PrEP?

At the moment PrEP is not available in Ireland.


In Ireland, it is illegal to supply medication by mail order, including over the internet. The Health Products Regulation Authority provides information for the public in relation to sourcing medication over the internet which is available here.


We recently updated our information about getting PrEP online. You can read that here.


PrEP has recently been made available in Scotland. For more information about PrEP we recommend you check out the website.

What you need to do before taking PrEP?

Please talk to a health advisor, nurse or doctor at the clinic. They can help you if you are planning to take, or are already taking PrEP.


It is really important to have an HIV test before or as you start.


PrEP can only be used if you are HIV negative. If you are already HIV positive and don’t realise it, you could develop resistance to drugs that you will need for treatment.


Ask for a ‘4th generation’ HIV blood test. This is also called a ‘combined antigen/antibody’ test. This tells you your HIV status approximately 4 weeks ago. Most finger prick tests are currently ‘3rd generation’. They tell you your HIV status approximately 3 months ago. So don’t rely on a fingerprick test alone before you start PrEP.


If you are just starting PrEP and had a risk in the last 4 weeks, have another 4th generation HIV blood test 4 weeks after starting, just to be sure an early infection was not missed. Don’t start PrEP if you have flu-like symptoms and a recent HIV risk. This is to check that these symptoms are not related to a recent HIV infection (ie seroconversion).


If you are starting PrEP after PEP, it is best to start immediately if you have ongoing risks. Ideally you should have an HIV blood test around the time you finish PEP/start PrEP plus another HIV blood test 4 weeks into PrEP.


Remember that unprotected sex while taking PrEP will reduce your risk of HIV but not other STIs, use condoms to reduce your risk of other STIs.


You will also need to have your kidney function checked. Kidney monitoring just involves a blood test for creatinine, and a urine test for protein. These should ideally be done just before or on the day you start.

What you need to do while taking PrEP

Once you have started PrEP, monitoring is important.


Every 3-4 months:

  • Have a ‘4th generation’ HIV blood test. This is also called and ‘antigen/antibody’ HIV blood test.
  • Have a full screen for other sexually transmitted infections (STIs).
  • Have a urine dipstick test for protein when you have your STI check up; if there is more than a trace, an additional blood or urine test can be sent off for kidney function.

Every 12 months:

  • Have a blood test to check your kidney function.
What about other sexually transmitted infections?

Research has shown that PrEP is highly effective at preventing HIV as long as it’s taken as directed.


However, PrEP will not protect you from other sexually transmitted infections (STIs) whereas condoms will. If you’re using PrEP it’s important that you go for regular STI screens every three months so you can get any other infections treated.