PrEP

What is PrEP?

PrEP (short for pre-exposure prophylaxis) is a type of antiviral treatment that helps to protect you from getting HIV. It’s specifically for people who have an increased risk of getting HIV. So for example, if you have a HIV positive partner, you may benefit from taking PrEP daily in addition to using a condom.

HIV stands for human immunodeficiency virus. It’s a type of sexually transmitted infection. The HIV virus damages cells in your immune system, which puts you at greater risk of getting infections or disease. PrEP interferes with the virus’ reproduction, to keep your immune system protected.

With PrEP, you can also do what’s called ‘event-based dosing’. For example, if you’re going on holiday and likely to be having sex with casual partners, there’s a way you can take it called ‘holiday PrEP’ or ‘on-demand PrEP’, where you take it for a short period of time to increase your protection.

PrEP is available as a branded tablet (Truvada) and as a generic pill (Emtricitabine/Tenofovir disoproxil). The way they work should be the same, but the way the tablet looks and the company that makes them are different. Generic PrEP also tends to be much cheaper.

How does PrEP work?

Pre-exposure prophylaxis contains two active ingredients: emtricitabine and tenofovir. In short, to protect from HIV PrEP stops an enzyme that the virus needs to replicate itself. When HIV is transmitted from one person to another, there’s an ‘incubation period’ where these viral cells convert their own genetic material from RNA into DNA. The medicines in PrEP interfere with this process, to stop the virus from developing. This should help you stay HIV negative.

Who should take PrEP?

Pre-exposure prophylaxis is recommended if you’re HIV negative but experience situations where you’re at high risk of contracting HIV.

Taking PrEP may help you if:

• Your partner has a detectable viral load of HIV
• You’re planning on having unprotected sex with casual partners
• You’re having sex with someone with an unknown HIV status
• You share needles or injection equipment with other people.

But if you’ve tested positive for HIV PrEP isn’t appropriate, because the dose isn’t high enough to suppress the virus. The treatment for this is very similar to PrEP medication, but the dose and the way you take it is different. You can take a test to check if you’re HIV negative at a local sexual health clinic, or by speaking to your GP. You’ll just need a blood test 18-45 days after you think you were exposed, or a finger stick test 18-90 days after exposure to test for antigens/antibodies.

Before you begin taking PrEP medication, you take a hepatitis B test. The active ingredient in PrEP can work to treat hepatitis B as well – but it’s not a high enough dose to control the virus. This can lead to the virus becoming resistant to treatment in the future.

If you stop taking PrEP medication for any reason if you have hepatitis B, it can also cause it to flare and affect your liver function. If your test is clear, then you should get a hepatitis B vaccination series to protect you from infection while you’re using PrEP.^[1]

You should also let your clinician know if you’re using any recreational drugs before taking PrEP. While you’re using PrEP drugs can work differently – and taking them at the same time can increase your risk of side effects.

How effective is PrEP?

Clinical studies have found that taking PrEP can reduce the risk of HIV infection by 86%.^[2] Taken daily, it’s been estimated to be 88-90% effective, if not higher.^[3]

If you take it every day, it takes seven days for PrEP to become fully effective at preventing transmission of HIV infection through anal sex. If you’re a woman taking it for vaginal sex, it takes 21 days.

How should I take PrEP?

There are four different ways to take PrEP to protect from sexually transmitted infections. The way you take it will largely depend on how and when you plan to have unprotected sex.

Daily use is the most effective, but isn’t the only way of taking PrEP medication. If you’re not having sex regularly, taking PrEP in another way that means you take less tablets can still be effective, and ultimately save you money. If you’re not sure what the best way to take it is, let us know, and we’ll give you the advice you need.

If you’re taking PrEP over a long period, you’ll also need to get tested regularly to make sure you’re still HIV negative. This is a blood test usually done every three months. You can take a HIV test at your local sexual health clinic, a HIV testing centre, or speak to your GP.

Daily use

Like the name suggests, daily use of PrEP is where you take one pill every day at the same time. It’s suitable for you if you’re having anal or vaginal sex. Your protection starts after seven days of taking it like this. It’s a good way to protect yourself from HIV infection if you’re having sex regularly with an infected person.

T’s and S’s

T’s and S’s is where you take PrEP on specific days of the week: Tuesday, Thursday, Saturday and Sunday. It’s only suitable for anal sex and is a good form of protection if you have sex once or twice a month.

If you’re doing daily use or T’s and S’s, you should take your pill at the same time every day.

On-demand

Also called ‘event-based dosing’, on-demand is where you take:

• two pills 2-24 hours before you plan to have unprotected sex
• one pill 24 hours later
• and continuing to take one pill every 24 hours until you go two days without having sex.

It’s helpful if you know you’re having unprotected sex 24 hours in advance, but is only suitable for you if you’re having anal sex.

7-7-7

The 7-7-7 method, sometimes called ‘holiday PrEP’, is for when you plan to have sex multiple times, with multiple partners, within a short space of time. You’ll take one tablet a day for:

• seven days before you ‘go on holiday’ (or your period of having sex starts)
• every day during your holiday (your period of having sex)
• and for seven days after your holiday (after your period of having sex finishes)

So the 7-7-7 name is based on your holiday lasting seven days, but it may be longer or shorter than this. It’s suitable for both vaginal and anal sex.

Can you take PrEP if you are HIV positive?

You shouldn’t take PrEP if you’re HIV positive, because it won’t help to suppress the virus in your body – it isn’t a HIV treatment. To do this, the dose needs to be stronger. In fact, if you take PrEP but are HIV positive, it could make the drug less effective overall, because the dose is at a size where the virus can learn how to become resistant to it.

So if you’re HIV positive, you should speak to your GP or sexual health clinic about getting the HIV treatment that’s right for you.

If you think you’ve been exposed to HIV recently (within 72 hours), post-exposure prophylaxis (PEP) could stop the virus taking hold. The same medicine can be used for pre- and post-exposure prophylaxis, but how you take it is different. You’ll typically take PEP three to five times a day for 28 days after you’ve been exposed to HIV. Speak to a clinician or sexual health clinic as soon as possible if you think you might have been exposed to HIV.