Pre-exposure Prophylaxis (PrEP)

Taking PrEP before being exposed to HIV means there’s enough medication inside you to block HIV if it gets into your body – before it has the chance to infect you.

PrEP is for anyone who is HIV negative, sexually active, doesn’t always use condoms and wants to protect themselves from HIV. PrEP can also be used by people who inject drugs and share injecting equipment.

Some of the people who could benefit from using PrEP include:

• Heterosexual men and women who may be having sex without using condoms with partners who may have HIV and are not on treatment.
• People who are HIV negative who are having sex without using condoms with partners who have HIV but do not have undetectable levels of HIV in their blood.
• Gay, bisexual and other men who have sex with men who may have sex without using condoms.
• Trans men, trans women and non-binary people who may be having sex without using condoms with partners who may have HIV and are not on treatment.
• People who inject drugs and who may share injecting equipment.

You should always take PrEP as it is prescribed by the doctor or PrEP provider you are getting your PrEP from.

At the moment most PrEP is prescribed in pill form but soon the medication could be available as a long acting injection that provides protection for a couple of months or more. While in other countries PrEP is available as a vaginal ring this is not available in the UK and this isn’t likely to change.

All of the following information about how much PrEP to take and how often to take it is only about taking it in pill form.

Starting PrEP

You will need to have an HIV test to show that you are HIV negative before you start using PrEP.

You have a choice about whether you take the PrEP pill every day, four times a week or as and when you need it which is called ‘on-demand dosing’ where you take PrEP before and after sex. This will depend on what is appropriate for you.

You can talk with a doctor or PrEP provider to help you understand what the best and most appropriate way for you is to take PrEP.

Real life experience shows that everyone can start with a double dose (two pills) of the medication, two to 24 hours before sex. After two hours you are protected from HIV

This is the same for people who inject drugs, so to start with a double dose (two pills) of the medication two to 24 hours before drug use.

Although PrEP is highly effective at preventing HIV, it doesn’t provide protection from other STIs or an unplanned pregnancy.

It’s important if you’re using PrEP that you go for regular HIV and STI screenings every three to six months.

Stopping PrEP and starting again

PrEP can be stopped and re-started according to your needs.

For people with a penis you will need to continue the pills for at least two daily doses after vagina/frontal/anal sex before stopping.

For people with a vagina/front hole it’s currently recommended to continue taking the pills for at least seven days before stopping.

The new recommendations are that if it has been less than seven days since your last dose, you can start retaking PrEP as you were taking it before – so on a daily basis, either four or seven days a week.

If it has been longer than seven days since you last took any PrEP, then restart by taking a double dose of pills (two pills) and then continue with your chosen way of using PrEP - either four or seven days a week.

Talk with your doctor or PrEP provider about stopping PrEP in your situation.

Support for taking PrEP

It can sometimes be easy to miss taking your dose of any medication, PrEP included, and there are ways that can support you to remember to take your doses.

Many people use pill boxes that are sectioned into days (also known as dossete boxes) to put their pills in. You can get a range of options for these at your local pharmacists.

If you are taking PrEP four times a week you can use a system called ‘T’s and S’s’ which is taking a pill on every day that starts with a T and an S – so Tuesday, Thursday, Saturday and Sunday.

It helps to take the pills around the same time every day, or with other pills that you may be taking like the contraceptive pill or your GAHT. There are a couple of apps you can download to your phone that will ping you an alarm to remind you to take your dose. These include PrEP Emerge and PrEPtime.

PrEP is available from sexual health clinics in England for anyone who may be more likely to be exposed to and acquire HIV from their sexual partners or their injecting drug use. You should check with your local service to find out which clinics are providing PrEP.

PrEP and the tests you take before you are prescribed it are free on the NHS no matter your immigration status.

If you’re thinking about getting PrEP from outside the NHS there are a number of things to consider, you can find more information from I Want PrEP Now.

If you buy your own PrEP online it’s important that you understand how to take PrEP in a way that works for you and gives you protection. You can talk with a doctor at the clinic you get tested at for HIV and STIs to help you understand the best way to take PrEP for you.

The drugs used in PrEP are the same drugs that are prescribed to thousands of people living with HIV every year. They’re very safe and serious side effects are very rare.

A few people experience nausea, headaches or tiredness which normally goes away in-between a week and a month. Very rarely, the medication can affect kidney function, which is why tests are carried out on a regular basis..

In most large studies no one has become infected if they took PrEP as recommended. However, if you don’t follow the correct dosing regimen it may not work.

This issue will be discussed more fully with you when your doctor prescribes PrEP for you, but it does not have any negative effects or interactions with other drugs, so there are no problems taking PrEP while you are taking:

• Pharmaceutical contraception (‘the pill’), Emergency Contraception, Hormone Replacement Therapy or Gender Affirming Hormones.
• Drugs taken recreationally, like marijuana, cocaine etc.
• Prescription drugs to treat other medical conditions you may have. If you have kidney issues or osteoporosis, you will be prescribed Descovy rather than Truvada. Your Doctor will talk with you about this when prescribing PrEP.

If you have Hepatitis B your doctor will discuss your use of PrEP and the best way to take it with you.

It’s safe to take PrEP when you are trying to get pregnant or are already pregnant or breastfeeding. PrEP won’t harm you or the baby/ies.

In England, the main PrEP drug that is prescribed is a generic version of Truvada, a drug used to treat HIV. A new drug, Descovy, has been approved for use as PrEP, although a generic version isn’t currently available, so it’s more expensive to use.

Both Truvada (including the generic version) and Descovy are as effective as each other in protecting you against HIV. You would only be prescribed Descovy if you have ongoing kidney issues; have osteoporosis or are under 18, as Truvada can affect kidney function and bone growth and/or density. Descovy isn’t prescribed for people born female as no research has been completed to show that its effectiveness at preventing HIV transmission for them.

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