What is tenofovir disoproxil fumarate?
Tenofovir disoproxil fumarate (TDF) is a medication used to treat HIV. It is taken in combination with other antiretroviral drugs.
There are two versions of tenofovir. The older version (TDF) was originally marketed as Viread. Generic versions of TDF are now also available.
The usual adult dose of TDF is one 245mg tablet per day.
A more recent version of tenofovir, tenofovir alafenamide fumarate (TAF), is available as part of combination tablets. TAF is combined with other antiretroviral drugs in Descovy, Genvoya and Odefsey.
How does TDF work?
TDF is a nucleotide reverse transcriptase inhibitor (NRTI or NtRTI). Your doctor will prescribe TDF as part of your HIV treatment, along with antiretrovirals from another class of drugs. It is important to take all the drugs as prescribed, every day. Each drug class works against HIV in a different way.
The aim of HIV treatment is to reduce the level of HIV in your body (viral load). Ideally, your viral load should become so low that it is undetectable – usually less than 50 copies of virus per ml of blood. Taking HIV treatment and having an undetectable viral load protects your immune system and stops HIV being passed on during sex.
How do I take TDF ?
You should take TDF with food.
HIV treatment works best if you take it every day. When would be a good time for you to plan to take your treatment? Think about your daily routine and when you will find it easiest to take your treatment.
If you forget to take a dose of TDF, take it as soon as you remember. If it has been more than 12 hours since your dose was due, then don’t take a double dose, just skip the dose you’ve forgotten and carry on.
If you regularly forget to take your treatment, or you aren’t taking it for another reason, it’s important to talk to your doctor about this.
What are the possible side effects of TDF?
All drugs have possible side effects. It’s a good idea to talk to your doctor about possible side effects before you start taking a drug. If you experience something that might be a side effect, talk to your doctor about what can be done. A full list of side effects, including less common side effects, should be included in the leaflet that comes in the packaging with tenofovir.
We generally divide side effects into two types:
Common – a side effect that occurs in at least one in a hundred people (more than 1%) who take this drug.
Rare – a side effect that occurs in fewer than one in a hundred people (less than 1%) who take this drug.
Common side effects of TDF include (most common in bold):
- diarrhoea, being sick (vomiting), feeling sick (nausea), dizziness, rash, feeling weak, decreases in phosphate in the blood, headache, abdominal pain, feeling bloated, flatulence, liver problems.
Rare side effects of TDF include: bone thinning, kidney problems.
Does TDF interact with other drugs?
You should always tell your doctor and pharmacist about any other drugs or medication you are taking. That includes anything prescribed by another doctor, medicines you have bought from a high-street chemist, herbal and alternative treatments, and recreational or party drugs (‘chems’).
Some medicines or drugs are not safe if taken together – the interaction could cause increased, dangerous levels, or it could stop one or both of the drugs from working. Other drug interactions are less dangerous but still need to be taken seriously. If levels of one drug are affected, you may need to change the dose you take. This must only be done on the advice of your HIV doctor.
Any drugs that are known to have interactions with TDF will be listed in the leaflet that comes in the packaging with TDF. Tell your doctor if you are taking any of these drugs, and other drugs that are not on the list.
You should not take TDF with adefovir dipivoxil, used to treat hepatitis B.
It’s important your doctor knows about any other drugs you are taking that might increase your risk of kidney problems. This includes creatine supplements used to increase exercise performance, as they can interfere with the results of kidney function blood tests. There are other drugs that might affect your kidneys – it’s important to tell your doctor if you are taking any of the following drugs:
- adefovir dipivoxil
- amphotericin B
- non-steroidal anti-inflammatory drugs (NSAIDs)
Can I take TDF in pregnancy?
If you are considering having a baby, or think you might be pregnant, talk to your doctor as soon as possible about which combination of anti-HIV medications would be right for you. It is important to take antiretroviral treatment during pregnancy to prevent passing HIV from mother to baby.
Concerning TDF, BHIVA recommends that women who are already taking anti-HIV medications and become pregnant can usually continue to take the same medication throughout their pregnancy. In addition, BHIVA lists TDF (in combination other medications) as an option that may be recommended for women who start HIV treatment in pregnancy, depending on their individual circumstances.
Can children take TDF?
TDF is approved for use in children aged 12 years and over. Reduced strength tablets are available for 6-12 year olds and granules for 2-12 year olds.
Talking to your doctor
If you have any concerns about your treatment or other aspects of your health, it’s important to talk to your doctor about them.
For example, if you have a symptom or side effect or if you are having problems taking your treatment every day, it’s important that your doctor knows about this. If you are taking any other medication or recreational drugs, or if you have another medical condition, this is also important for your doctor to know about.
Building a relationship with a doctor may take time. You may feel very comfortable talking to your doctor, but some people find it more difficult, particularly when talking about sex, mental health, or symptoms they find embarrassing. It’s also easy to forget things you wanted to talk about.
Preparing for an appointment can be very helpful. Take some time to think about what you are going to say. You might find it helpful to talk to someone else first, or to make some notes and bring them to your appointment.
For detailed information on this drug, visit the tenofovir disoproxil fumarate page in the A-Z of antiretroviral medications.