PrEP: The HIV prevention drug

Learn how PrEP can help to prevent the transmission of HIV

Written by spunout


PrEP is a medicine which is taken to reduce the chance of getting HIV. It works by having enough of the drug in your body that if you are exposed to HIV, it can block it before it has a chance to infect you. Taking PrEP once every day reduces the risk of getting HIV from sex by more than 90% and by more than 70% among people who inject drugs.

HIV can be transmitted through:

  • Unprotected sex (vaginal, anal and oral)
  • Blood-to-blood contact (using contaminated needles, blood transfusions in countries where blood is not screened)
  • During pregnancy, childbirth or breastfeeding from parent to child

Learn more about HIV here.

PrEP does not stop you from getting other STIs so it is not a replacement for condoms. Using condoms every time you have sex is the best way to prevent you from getting or passing on STIs. Since November 2019 PrEP is now available for free in Ireland through the HSE for people who meet specific criteria. You can find out more about who is eligible for free PrEP below. 

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Who can benefit from taking PrEP

In 2018 79% of HIV diagnoses were male and 21% were female.

You can benefit from taking PrEP:

  • If you are HIV negative and don’t always use condoms
  • If you are having sex without a condom with HIV positive partners
  • If you are having sex with many partners, or a partner whose HIV status is unknown
  • If you are using recreational drugs for sex (crystal meth, mephedrone or GHB) also known as ChemSex
  • If you inject drugs and share needles or equipment to inject drugs

Before taking PrEP

If you are thinking about taking PrEP you should speak to a healthcare professional.

It is important to have a HIV test before you start PrEP and then regular tests when you are taking PrEP. It is also important to test for hepatitis B because PrEP medicines fight against both HIV and hepatitis B and the medicine needs to be taken more carefully if you have hepatitis B. Getting vaccinated against hepatitis A and B is recommended for men who have sex with men and people who inject drugs or to boost a vaccine you have had before.

Before taking PrEP you should also get a blood and urine test to check your kidneys for creatinine and have a test for other STIs.

Taking PrEP

There are different ways you can take PrEP.  The most common and effective way is taking one pill a day, every day.  This is the only recommended way for people who inject drugs or who have hepatitis B.

When you start taking PrEP you have to get the drug levels high enough in your body before it begins to protect you.

Anal Sex

  • If you are having anal sex you need to take at least two tablets of PrEP between two and 24 hours before having sex
  • Taking PrEP two to 24 hours before sex makes sure that the drug levels are high enough to protect you
  • You then need to take PrEP continually every day after that
  • If you decide to stop taking PrEP, do not do so until 48 hours after the time of unprotected anal sex

Vaginal Sex

  • If you are having vaginal sex you need to take PrEP daily
  • You need to begin PrEP seven days before sex for the drugs to reach the level that give the highest protection
  • This is because PrEP does not get into vaginal tissues as well as it gets into rectal tissues
  • If you decide to stop taking PrEP, do not do so until seven days after the time of unprotected vaginal sex

Injecting/ Slamming drugs

  • Daily PrEP (one pill a day, every day) is the only recommended way for people who inject drugs
  • If you decide to stop taking PrEP do not do so until seven days after the last risk of HIV

Event Based Dosing

Event Based Dosing is when you do not take PrEP continuously but only when you know you are going to have condomless anal sex.

For anal sex you take two pills between two and 24 hours before sex, and a single pill 24 hours and 48 hours after.

The before sex dose is very important to make sure there is enough medicine in your body to protect you when you have sex. You then need to take one pill every 24 hours for the days you are having condomless anal sex.

EBD is not suitable for vaginal sex.

EBD is not suitable if you have hepatitis B.

Missing a pill while on PrEP

If you miss one or two pills don’t stop taking PrEP, just start again once you remember. There should be enough of the drug in your body to protect against HIV.

If you are missing more than a couple of doses each week you are not going to be protected.

To help remember to take PrEP regularly try your best to make it part of your routine, in the morning when you are brushing your teeth or at lunch time.

If you stop taking PrEP and have condomless sex during this time you should consider taking PEP and having another HIV test.

Taking care of yourself while on PrEP

If you are taking PreP, every three months you should have:

  • A HIV blood test
  • A full screen for other STIs
  • Have your urine tested for protein and if there is any found have additional blood tests done to check your kidneys

Every 12 months:

  • Have blood tests to check your kidney functions
  • Have a hepatitis C test

Stopping HIV PrEP

If you decide to stop taking PrEP there are several steps you should take:

  • Discuss your plans with your healthcare provider
  • Discuss your plans with any regular sex partners
  • Get HIV and STI tested

Who can get free PrEP in Ireland?

Am I eligible to get PrEP?

To get PrEP for free through the HSE you need to:

  • test negative for HIV
  • be able to attend for a check-up at least once every 3 months
  • meet at least one of the following criteria for free PrEP

Criteria for free PrEP in Ireland 

1. You are having sex without condoms with HIV-positive partners who:

  • are not on HIV treatment, or
  • are on treatment but not virally suppressed (do not have an ‘undetectable’ viral load)

2. You are a man who has sex with men – this includes trans men who have sex with men, or a trans woman who has sex with men and meet any one of the following:

  • had anal sex without condoms with more than one partner in the last 6 months
  • had an STI in the last year
  • used HIV PEP (post-exposure prophylaxis) in the last year
  • used recreational drugs for sex (also known as chemsex) in the last 6 months

3. You are a heterosexual man or woman who is considered by a specialist STI doctor, to be at significant risk of acquiring HIV through sex.

Monitoring clinics for PrEP in Dublin

There are two PrEP monitoring clinics in Dublin where you can get the PrEP prescription:

GPs can also prescribe PrEP but not all may be aware of the drug.

For more information on PrEP in Ireland visit HIV Ireland

Feeling overwhelmed and want to talk to someone?

If you are a customer of the 48 or An Post network or cannot get through using the ‘50808’ short code please text HELLO to 086 1800 280 (standard message rates may apply). Some smaller networks do not support short codes like ‘50808’.

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