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Enfuvirtide for HIV


Enfuvirtide slows the progress of HIV infection.

It is one of a number of medicines that you will need to take regularly.

It is given by subcutaneous injection. You will need two injections each day.

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About enfuvirtide

Type of medicine

A fusion inhibitor antiretroviral medicine

Used for

Human immunodeficiency virus (HIV) infection in adults and in children over 6 years of age

Also called


Available as

Subcutaneous injection

Enfuvirtide is an antiretroviral medicine. It is used for human immunodeficiency virus (HIV) infection. It slows the progress of HIV infection, but it is not a cure. HIV destroys cells in the body, called CD4 T cells. These cells are a type of white blood cell and are important because they are involved in protecting your body from infection. If left untreated, the HIV infection weakens your immune system so that your body cannot defend itself against bacteria, viruses and other germs. Enfuvirtide is known as a fusion inhibitor antiretroviral medicine - it works by stopping HIV from attaching to your CD4 cells to get inside them. By reducing the amount of virus getting into your cells, it helps to maintain the health of your immune system.

Enfuvirtide will be prescribed for you by a doctor who is a specialist. It is given alongside a number of other antiretroviral medicines, as part of a combination therapy. Taking three or more antiretroviral medicines at the same time is more effective than taking one alone. Taking a combination of different medicines also reduces the risk that the virus will become resistant to any individual medicine. It is vital to take them exactly as prescribed to maintain success and to help to prevent the virus from becoming resistant to the medicines. These medicines are usually taken for life.

Before using enfuvirtide

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start using enfuvirtide it is important that your doctor knows:

  • If you are pregnant or breastfeeding.

  • If you have any problems with the way your liver works.

  • If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

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How to use enfuvirtide

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about enfuvirtide and how to administer it, and it will also provide you with a full list of the side-effects which you could experience from having it.

  • Use enfuvirtide exactly as your doctor tells you to. The usual dose for an adult is 90 mg twice a day. This is given as a 1 ml injection just under the skin (subcutaneous injection) on your upper arm, the outside of the upper part of your thigh, or your stomach area (abdomen). If you are giving enfuvirtide to a child, you will be told how much of the injection to give for each dose.

  • Each injection should be given at a different site to your last few injections. You should never use an area of your skin where there is still a reaction from a previous injection.

  • Spread the timing of your injections evenly over the day. The ideal times to give the injections are first thing in the morning, and then early evening.

  • If you forget to have a dose at the correct time, have it when you remember, unless it is less than six hours before your next dose is due. In this case, do not have the missed dose.

How to use Fuzeon®

  1. Open the syringe pack and remove the caps on the vials.

  2. Wash your hands well and then clean the top of each vial with an alcohol wipe.

  3. Using the large (3 ml) syringe, push back the coloured needle protection and remove the clear plastic cap. Draw 1.1 ml of air into the syringe and then insert the needle into the vial of water for injections.

  4. Press the plunger releasing the air into the vial and then turn the vial (with the syringe still attached) upside down. Make sure the tip of the needle is in the water.

  5. Slowly pull back the plunger to fill the syringe with 1.1 ml of water. Tap the syringe gently to remove any air bubbles and then check again to make sure you have 1.1 ml of water in the syringe.

  6. Remove the syringe from the vial of water. Be careful not to touch the needle with anything as you do this.

  7. Insert the needle into the vial of enfuvirtide powder, and press the syringe plunger in slowly to release the water gently into the powder. Do not shake or invert the vial.

  8. Remove the syringe from the vial, cover the needle with the needle protection and dispose of it into a safe container.

  9. Leave the vial of powder to dissolve - this may take 45 minutes. Tap the side of the vial gently to remove any bubbles and make sure the solution is particle-free.

  10. Wherever possible, you should inject the solution straight after it has been prepared. If you are unable to do this, the made-up injection can be kept in a fridge, at 2-8ºC, for up to 24 hours. Do not keep reconstituted injections for longer than this.

  11. To administer the injection, wipe the top of the vial again with a clean alcohol swab. Remove the clear plastic cap from the small (1 ml) syringe and draw 1 ml of air into the syringe. Insert the needle into the vial, inject the air into the vial, then turn the vial upside down and gently withdraw 1 ml of solution into the syringe (or the amount your doctor has prescribed).

  12. Remove the syringe from the vial and inject the solution under your skin as you have been directed. Remember to cover the needle with the needle protection after you have finished and dispose of the syringe into a safe container.

Getting the most from your treatment

  • Keep your regular appointments with your doctor so that your progress can be monitored. You will need to have regular blood tests.

  • It is important that you have enfuvirtide and your other antiretroviral treatment regularly. This will help to prevent the HIV from becoming resistant to the medicines you are taking. Even if you miss only a small number of doses, the virus can become resistant to treatment.

  • If you develop any infection soon after you start the treatment, let your doctor know. As a result of taking antiretroviral medicines, your immune system may start fighting an infection which was present before you started the treatment, but which you may not have been aware of.

  • Follow carefully any advice your doctor gives to you about making lifestyle changes to reduce any risk of damage to your heart and blood vessels. These can include stopping smoking, eating healthily and taking regular exercise.

  • Although treatment with antiretroviral medicines can reduce the risk of you passing HIV to others through sexual contact, it does not stop it. It is important that you use condoms.

  • It is not uncommon for people with HIV to feel low or even depressed, especially soon after the diagnosis has been made and treatment has been started. If you have any feelings of depression you should speak with your doctor straightaway.

  • Some people who have taken antiretroviral medicines (particularly over a long time) have developed a condition called osteonecrosis. This is a bone disease where bone tissue dies because there is a reduced blood supply to it. It leads to joint pains and stiffness, and can cause difficulties in movement. If you notice any of these symptoms, speak with your doctor.

  • If you buy any medicines or herbal remedies 'over the counter', check with a pharmacist that they are suitable to take alongside enfuvirtide and your other medicines. This is because some medicines interfere with antiretrovirals and can stop them from working properly.

  • If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

  • Treatment for HIV is usually lifelong. Continue to use enfuvirtide regularly, even if you feel well. This is to keep your immune system healthy.

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Can enfuvirtide cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with enfuvirtide. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common

enfuvirtide side-effects

(these affect more than 1 in 10 people)

What can I do if I experience this?

Pain or tenderness, swelling, redness, bruising, itchiness and skin bumps where the injection has been given

Most people experience injection-site reactions. If any become troublesome, speak with your doctor

Loss of weight, tingling or numb feelings

If troublesome, let your doctor know


enfuvirtide side-effects

(these affect fewer than 1 in 10 people)

What can I do if I experience this?


Drink plenty of water to replace lost fluids

Feeling sick (nausea), indigestion

Stick to simple meals - avoid fatty or spicy food. If it continues, speak with your doctor

Flu-like infections, blocked nose, conjunctivitis

Ask your doctor to recommend a suitable remedy

Feeling weak or dizzy, loss of concentration

Do not drive and do not use tools or machines while affected

Loss of appetite, kidney stones, muscle aches and pains, skin problems, feeling anxious or irritable, shaking, inflamed pancreas, nightmares

If any of these become troublesome, let your doctor know

Changes to some blood tests

Your doctor will check for this

Important: some people taking enfuvirtide have developed an allergic-type reaction. If you experience the following, stop using the injections and contact your doctor for further advice straightaway:

  • A skin rash, high temperature, sickness (vomiting), sweating or chills, muscle stiffness or shaking, breathing problems, and feeling dizzy.

If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.

How to store enfuvirtide

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never use more than the prescribed dose. If you suspect that you might have taken an overdose of this medicine, or someone else has taken some by accident, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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