Emtricitabine/tenofovir (PrEP)

Emtricitabine/tenofovir is a medication that’s used to control HIV. The name of it refers to the active ingredients it contains: emtricitabine and tenofovir. It’s taken as a pre-exposure prophylaxis (PrEP) to prevent those with a high risk of exposure to HIV from catching it.

Emtricitabine/tenofovir does not cure HIV, although it can be used as part of treatment for those with HIV to prevent the infection spreading further.

What is Truvada?

Truvada is a branded version of emtricitabine/tenofovir. This means they work in the exact same way and they are just as effective as each other, only they may contain different non-active ingredients, and have a different name and price. Truvada is most commonly available in the US, whereas the unbranded ‘generic PrEP’ (emtricitabine/tenofovir) is more widely prescribed in the UK than Truvada.

Emtricitabine/tenofovir are antiviral drugs that work by protecting the body’s immune cells from HIV. The medication blocks the activity of the enzymes responsible for HIV and stops the virus from growing and spreading to other body cells. These medications do not cure HIV, but can help to prevent the infection if you have been exposed to it.

How long does emtricitabine/tenofovir take to work?

You can take a double dose 2 hours before having sex. You can then continue taking 1 tablet each day, starting about 24 hours after your double dose, or you can choose to use an “on demand” schedule. The number of days you take PrEP for after sex when taking PrEP on demand depends on the type of sex you have.

Missing a dose of emtricitabine/tenofovir can make the medication less effective if taking this “on demand”.

How long does emtricitabine/tenofovir stay in your system?

The half-life of emtricitabine is approximately 10 hours, and the half-life of tenofovir is around 12 to 18 hours, meaning the medication takes about 4 to 5 days to leave your system.

Emtricitabine/tenofovir is up to 99% effective when taken daily (daily dosing). On average, for all types of dosing, PrEP is 86% effective at preventing HIV infection when taken as instructed.

Is emtricitabine/tenofovir effective after exposure?

If you’ve been exposed to HIV, and you’re taking PrEP as prescribed, you should be protected from the virus.

If you’re not currently taking PrEP and you think you’ve been exposed to HIV, you may need to start taking PEP (post-exposure prophylaxis) instead, not PrEP.

You should visit your local sexual health clinic for this. If it’s outside of normal working hours, go to your local A&E department instead. You need to start PEP within 72 hours of a potential exposure.

Is emtricitabine/tenofovir safer than condoms?

Emtricitabine/tenofovir only protects you from HIV. Using a condom also offers protection from a range of STIs, as well as HIV.

It’s recommended that you get tested for STIs every 3 months, including an HIV test.

Is undetectable HIV safe?

Studies have shown that people with an undetectable HIV viral load cannot pass on the virus to others. An ‘undetectable viral load’ means that the amount of the virus in their blood is not able to be found.

The PARTNER 2 study found that people taking effective HIV treatment with an undetectable viral load, did not pass on the virus to their sexual partners.

How you take PrEP will depend on whether you plan to take it daily or on demand. What works best for you will depend on what a doctor recommends is suitable for your health, lifestyle, and needs.

If your PrEP request is approved, carefully read the patient information leaflet that comes with your medication once you receive it. Do this before taking emtricitabine/tenofovir for the first time.

Recent updates made to national PrEP guidelines mean that anybody eligible for PrEP (emtricitabine and tenofovir) can now start it with a double dose and become protected within 2 hours. This includes using PrEP on demand (around the time of having sex).

How you take PrEP will depend on whether you plan to take it daily or on demand. What works best for you will depend on your lifestyle and needs.

Daily

When you take PrEP daily, you should:

• start by taking 2 tablets at least 2 hours before you have sex
• then take 1 tablet every day around the same time daily
• begin your daily dose ideally 24 hours after your initial double dose to stay protected from HIV

Daily PrEP is a great option if you do not like to plan sex or you do not want to worry about remembering to take PrEP when you do have sex, as it’s already part of your daily routine. Taking PrEP daily is also very effective in preventing HIV as it keeps you up to 99% protected from infection.

On-demand

On-demand means you only take PrEP when you need to, for example, if you have sex infrequently.

To do this, if you have anal sex or sex where you insert your penis, you:

• take 2 tablets at least 2 hours before having sex
• then, take 1 tablet each day, for 2 days – start taking your daily tablet around 24 hours after the initial double dose
• keep taking 1 tablet every 24 hours until you’ve not had sex for at least 2 days (known as 2:1:1 dosing)

2:1:1 dosing should not be used if you are receiving frontal (vaginal) sex or if you inject drugs, as it does not provide effective enough HIV prevention.

To do this, if you are a cis woman, trans, or non-binary person receiving frontal sex (and in people who inject drugs), you:

• take 2 tablets at least 2 hours before having sex
• take 1 tablet each day for 7 days following an initial double dose (known as 2:7 dosing) – start taking your daily tablet around 24 hours after the initial double dose
• keep taking 1 tablet every 24 hours until you’ve not had sex for at least 7 days

If you do not have sex regularly or do not want to remember to take a tablet every day, on-demand PrEP is a great way of making sure you’re protected from HIV when you need to.

Taking PrEP on demand can be just as effective as taking it daily, as long as you remember to take it on time. Missing even 1 tablet can reduce the effectiveness of your treatment.

Tuesday, Thursday, Saturday, and Sunday dosing (TTSS)

If you have already been using a daily dose of PrEP for at least 7 days, you can choose to take your dose on Tuesdays, Thursdays, Saturdays, and Sundays (known as TTSS dosing). This may be an option for you if event-based dosing is not right for you or if you get side effects when taking PrEP daily.

What dose of emtricitabine/tenofovir should you take?

The dose you take will depend on your lifestyle and health needs, and your doctor should advise. At ZAVA, we offer 200mg emtricitabine and 245mg tenofovir to be taken daily. These are provided together, so you do not need to request these separately.

What should you do if you miss a daily dose of emtricitabine/tenofovir?

If you take PrEP daily and forget to take your emtricitabine/tenofovir tablet for the day, take it as soon as you remember.

If you’ve been taking PrEP daily for a week or more, you’ll still get good protection if only taking 4 doses a week (TTSS dosing).

If you miss multiple doses or miss “on demand” doses, then contact your doctor or a sexual health clinic.

What should you do if you take too much emtricitabine/tenofovir?

If you take more than your prescribed emtricitabine/tenofovir dose, contact your GP, nearest sexual health clinic or call 111.

What is on-demand PrEP?

On-demand PrEP is taken only in situations where you have a high chance of getting HIV instead of taking it daily. This type of PrEP can provide effective protection for any form of sex, including vaginal/neovaginal or anal.

PrEP on-demand works on a 2-1-1 schedule if you have anal sex or give vaginal/ frontal sex. This means that you take:

• 2 pills at least 2 hours before you have sex
• 1 pill 24 hours after the first dose
• 1 pill 48 hours after the first dose

If you continue to have sex for a longer period of time, then you should also keep taking 1 pill every 24 hours until you have not had sex for 2 days.

PrEP on-demand for cis woman, trans, or non-binary people receiving frontal sex (and in people who inject drugs) works on a 2-7 schedule. This means that you take:

• 2 pills at least 2 hours before you have sex
• 1 pill 24 hours after the first dose
• 1 pill each day for the following 6 days

If you continue to have sex for a longer period of time, then you should also keep taking 1 pill every 24 hours until you have not had sex for 7 days.

We can prescribe emtricitabine/tenofovir to you if you are over 18 years old, have tested HIV negative, and have a higher risk of getting HIV. Our doctors will check that the treatment is suitable for you.

You might have a higher risk if you have sex without a condom with someone who has a higher risk of HIV, or you:

• are a man, non-binary person, or transwoman who has sex with men and do not always use condoms
• are HIV-negative, but your partner is HIV positive
• have sex with people from places where HIV is common
• are a black African woman or man
• inject drugs
• are a sex worker
• have recently migrated

Please note that there could be other factors that put you at a higher risk of getting HIV.

Who should not take emtricitabine/tenofovir?

If you have a low risk of getting HIV, you do not need to take emtricitabine/tenofovir.

If you are HIV positive, you should not take emtricitabine/tenofovir on its own, as you may develop resistance to full HIV treatment.

It may also be unsuitable to take emtricitabine/tenofovir if:

• you’re under 18 years old
• you have liver disease
• you have kidney disease
• you have an allergy to any of the ingredients in emtricitabine/tenofovir
• you’re taking any other type of antiviral medication
• you’re taking a regular high dose of anti-inflammatory painkillers
• you have any rare conditions relating to lactose intolerance
• you’re on a low-phosphate diet
• have osteoporosis

If you fall into any of these categories but you have a high risk of HIV exposure, talk to a doctor. They can tell you about appropriate ways to protect yourself.

Pregnancy and PrEP

If you are pregnant and feel you need to use PrEP, you should contact your midwife, GP or local sexual health clinic.

Can you take emtricitabine/tenofovir with other medications?

It’s important to tell your doctor about any medicines you’re taking before you start a course of emtricitabine/tenofovir. This includes any over-the-counter drugs.

Some medications may affect emtricitabine/tenofovir and cause problems with your kidneys. Talk to your doctor if you’re taking:

• any drugs for treating fungal infections
• any drugs for treating viral infections
• antibiotics
• painkillers like Ibuprofen
• medications for treating hepatitis C
• cancer drugs

Can you drink alcohol while taking emtricitabine/tenofovir?

Emtricitabine/tenofovir is not known to cause any interactions with alcohol, so you can still drink while taking it. However, note that if you do not drink alcohol in moderation while taking the medication, it may increase your chances of side effects.

ZAVA’s PrEP service is currently long-term out of stock, so we can’t offer PrEP online right now.

If you do decide to order PrEP online, make sure you use a regulated and trusted service so you can be sure you’re getting treatment which is safe and right for you.

Before you begin taking emtricitabine/tenofovir, our doctors will check whether you’ve had:

• a negative HIV test result
• a normal kidney function test result
• a negative hepatitis B and C test result — you only need a negative hepatitis B result if you’ve not had a hepatitis B vaccination, and you only need a negative hepatitis C result if you are a man who has sex with other men or are a trans woman or have other risk factors for hepatitis C

We will ask about these tests when you complete our online questionnaire to request treatment. Once you begin taking PrEP, you will need to repeat these tests at different periods too.

Why are these tests important?

HIV test

It may be unsafe to take PrEP if you’re HIV positive. The antiviral drugs in PrEP (emtricitabine and tenofovir) are often used to treat people with HIV, alongside other medications. You can become resistant to these drugs if you use them when you’re already HIV positive. This can make it more challenging to treat the infection later on.

If you have flu-like symptoms after unprotected sex, like a fever or a rash, you should check that you’re HIV negative before taking PrEP. You may need to take PEP instead if you’ve potentially been exposed to HIV in the last 72 hours. Scroll up to learn more (‘Is emtricitabine/tenofovir effective after exposure?’).

Different HIV tests have different timeframes for testing after unprotected sex. Follow the instructions for your chosen test to make sure the results are accurate.

Our HIV test kit is over 99% accurate at detecting HIV if you test 6 weeks after possible exposure to HIV. You can test any time before that, but if you get a negative result, you should repeat your test to make sure your results are accurate. If you have a potential exposure to HIV in the 6 weeks before starting PrEP, you should test again after 6 weeks, and then 3 months after starting PrEP.

Kidney function

The two antiviral drugs in PrEP are used by the body and then passed out in your urine through your kidneys. You need to check that your kidneys are working properly otherwise these drugs can build up in your body and cause damage.

Hepatitis B and C

If you have hepatitis, taking and subsequently stopping PrEP can lead to a flare up of liver inflammation and your hepatitis getting worse. It can also affect any future hepatitis treatment you receive and make it harder to treat your condition.

What are the side effects of emtricitabine/tenofovir?

As with all medications, emtricitabine/tenofovir can have side effects. These usually go away within a few weeks. Most people don’t experience any side effects.

Common side effects of emtricitabine/tenofovir include:

• feeling sick and being sick (vomiting)
• diarrhoea
• headaches
• dizziness
• feeling weak
• pain in the stomach
• feeling bloated
• problems with sleeping
• rashes or swelling of the skin

Less common side effects include:

• anaemia (a lack of red blood cells, or haemoglobin, in the blood)
• muscle weakness and pain
• yellow and itchy eyes
• pain in the bones
• joint stiffness
• back pain
• a condition called lactic acidosis, where lactic acid builds up in the body, causing drowsiness and difficulty with breathing

If you get any serious side effects or feel acutely unwell, you should seek an urgent in-person review with a doctor.

We offer further information about the following areas of HIV, covering:

• symptoms of HIV
• HIV skin rashes
• HIV testing and HIV test kits

The NHS has information on:

• HIV and AIDs

Terrence Higgins Trust provides information on:

• HIV therapy, support, and counselling

Naz offers information and support around:

• sexual healthcare to Black Asian and Minority Ethnic (BAME) communities

Depending on your background and circumstances, you can find more information:

• if you’re transgender through Mermaids
• about psychological therapies through the NHS
• about HIV prevention and works to fight against HIV stigma through the Gay men’s health project
• on drugs and chemsex from your local sexual health clinic or on Dean Street Clinic’s website

Several sources provide more information about PrEP and how it’s used. These include:

• iwantPrEPnow
• Prepster
• The PrEP Facts Facebook group