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AIDSinfo Drug Database

AIDSinfo Drug Database

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Enfuvirtide  Audio icon

Brand Name: Fuzeon
Other Names: T-20
Drug Class: Fusion Inhibitor
Approved Use: Treatment of HIV Infection

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Chemical Image:
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Molecular Weight: 4491.9149

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Enfuvirtide causes injection site reactions. Almost all people get injection site reactions with enfuvirtide, which usually are mild to moderate but occasionally can be severe. Reactions on the skin where enfuvirtide is injected include:

  • Itching.
  • Swelling.
  • Redness.
  • Pain or tenderness.
  • Hardened skin.
  • Bumps.

Contact your health care provider right away if you have signs of infection at an injection site (oozing, increasing heat, swelling, redness, or pain).

Enfuvirtide can cause serious side effects. These include severe allergic reaction and possibly pneumonia.

Contact your health care provider right away if you have any of the following symptoms that could be signs of a severe allergic reaction:

  • Trouble breathing.
  • Fever with vomiting and a skin rash.
  • Blood in your urine.
  • Swelling of your feet.
  • Any combination of rash, fever, nausea and vomiting, chills, shivering, and/or low blood pressure.

Contact your health care provider right away if you have any of the following symptoms that could be signs of pneumonia:

  • Cough.
  • Fever.
  • Trouble breathing, including rapid breathing or shortness of breath.

While taking enfuvirtide, it is important to keep all of your appointments with your health care provider.

What is enfuvirtide?

Enfuvirtide is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in adults and children 6 years of age and older. Enfuvirtide is for people whose HIV is not well controlled by ongoing treatment with other HIV medicines. Enfuvirtide is always used in combination with other HIV medicines.

Enfuvirtide belongs to a class (group) of HIV drugs called entry and fusion inhibitors. Entry and fusion inhibitors block HIV from getting into and infecting certain cells of the immune system. This prevents HIV from multiplying and can reduce the amount of HIV in the body.

By attaching to the gp41 protein on the outer surface of HIV, enfuvirtide blocks HIV from getting into and infecting the immune cells. 
HIV medicines can’t cure HIV/AIDS, but taking a combination of HIV medicines (called an HIV regimen) every day helps people with HIV live longer, healthier lives. HIV medicines also reduce the risk of HIV transmission.

What should I tell my health care provider before taking enfuvirtide?

Before taking enfuvirtide, tell your health care provider:

  • If you are allergic to enfuvirtide or any other medicines.
  • If you have any other medical conditions.
  • If you are pregnant or plan to become pregnant. Whether enfuvirtide can harm an unborn baby is unknown. Enfuvirtide should be used during pregnancy only if clearly needed. Talk to your health care provider about possible risks with taking enfuvirtide when pregnant.  
  • If you are breastfeeding or plan to breastfeed. Do not breastfeed if you are infected with HIV or are taking enfuvirtide.
  • If you are using hormone-based birth control (such as pills, implants, or vaginal rings). For more information, view the AIDSinfo HIV and Birth Control infographic.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Enfuvirtide may affect the way other medicines or products work, and other medicines or products may affect how enfuvirtide works.

How should I take enfuvirtide?

Enfuvirtide comes in powder form and is given as an injection (a shot). The enfuvirtide powder and everything needed to give the injection come in a convenience kit. The kit includes:

  • 60 vials of enfuvirtide powder. Each vial contains 108 mg of enfuvirtide powder. 
  • 60 vials of sterile water for injection.
  • 60 syringes for mixing.
  • 60 syringes for injecting.
  • Instructions for mixing and injecting enfuvirtide.
  • Patient information about enfuvirtide.

Take enfuvirtide according to your health care provider’s instructions. Before injecting enfuvirtide, you or your caregiver should be trained by a health care provider on how to mix and inject the medicine. Do not mix other medicines in the same syringe with enfuvirtide. If you are having a hard time mixing or injecting enfuvirtide, contact your health care provider.

Enfuvirtide should be injected under the skin in the upper arm, upper leg, or stomach two times a day. Do not inject enfuvirtide in the same area as you did the time before. Do not inject enfuvirtide into the following areas: near the elbow, knee, groin, or lower or inner buttocks; directly over a blood vessel; around the belly button, scar tissue, a bruise, a mole, a surgical scar, a tattoo, or a burn site; or where there is an injection site reaction.

If enfuvirtide is foamy or jelled after mixing, allow more time for it to dissolve. Do not inject enfuvirtide if you see particles floating in the vial after the medicine has been mixed. Enfuvirtide can be taken with or without food. Do not swallow enfuvirtide; it must be injected.

After injecting enfuvirtide, place used syringes in a special disposal container (called a sharps container). (Your health care provider or pharmacist can give you a sharps container.) Do not place used syringes in a trash can.

Always take enfuvirtide in combination with other HIV medicines.

If you take too much enfuvirtide, contact your health care provider or local poison control center (1-800-222-1222) right away, or go to the nearest hospital emergency room.

For more information on how to take enfuvirtide, see the FDA drug label from DailyMed. (DailyMed is a federal website that includes the most recent drug labels submitted to FDA.)

What should I do if I forget a dose?

If you miss a dose of enfuvirtide, take the missed dose as soon as you remember it. But if it is almost time for your next dose, skip the missed dose and just take your next dose at the regular time. Do not take two doses at the same time to make up for a missed dose.

What side effects can enfuvirtide cause?

Enfuvirtide may cause side effects. Most side effects from enfuvirtide are manageable, but a few can be serious. Serious side effects of enfuvirtide include severe allergic reaction, infected injection sites, and possibly pneumonia. (See the WARNING above.)

Other possible side effects of enfuvirtide include:

  • Injection site reactions, including itching, swelling, redness, pain or tenderness, hardened skin, or bumps. If the injection site reaction is severe or you have signs of infection at an injection site (oozing, increasing heat, swelling, redness, or pain), contact your health care provider right away.
  • Shooting nerve pain or tingling that lasts up to 6 months. This is likely caused by injecting enfuvirtide close to large nerves or near joints. (This side effect has been reported with use of the Biojector 2000 needle-free device to inject enfuvirtide.)
  • Bruising and/or collection of blood under the skin. (This side effect has also been reported with use of the Biojector 2000 needle-free device.)
  • Immune reconstitution inflammatory syndrome (IRIS), a condition that sometimes occurs when the immune system begins to recover after treatment with an HIV medicine. As the immune system gets stronger, it may have an increased response to a previously hidden infection.

Tell your health care provider if you have any side effect that bothers you or that does not go away.

These are not all the possible side effects of enfuvirtide. To learn more about possible side effects of enfuvirtide, read the drug label or package insert or talk to your health care provider or pharmacist.

The AIDSinfo fact sheet on HIV Medicines and Side Effects also includes information that may apply to enfuvirtide.

You can report side effects to FDA at 1-800-FDA-1088 (1-800-332-1088) or online at

How should enfuvirtide be stored?

  • Enfuvirtide vials that are not mixed with sterile water can be stored at room temperature, 59°F to 86°F (15°C to 30°C). Enfuvirtide should be refrigerated if it cannot be stored at room temperature.
  • The sterile water can be stored at room temperature, 59°F to 86°F (15°C to 30°C).
  • After enfuvirtide has been mixed with sterile water, the vial can be stored in a refrigerator for up to 24 hours.
  • Do not use enfuvirtide or sterile water after the expiration date on the vials.
  • Do not use enfuvirtide if the original seal on the convenience kit is broken or missing.
  • Throw away enfuvirtide that is no longer needed or expired (out of date). Follow FDA guidelines on how to safely dispose of unused medicine.
  • Keep enfuvirtide and all medicines out of reach of children.

Where can I find more information about enfuvirtide?

More information about enfuvirtide is available:

Manufacturer Information

Hoffman-La Roche; Genentech
Main number: 866-422-2377
Patient assistance: 877-436-3683

The above Patient Version drug summary is based on the following FDA label(s): Kit.

Last Reviewed: July 29, 2016

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