March 29, 2017
Recommended Topic Related To:


"CHICAGO — The long-acting injectable cabotegravir (ViiV Healthcare), a novel HIV prevention therapy, can persist in the body for more than a year in some people, surprising new data from the phase 2a ÉCLAIR study show.

"It's an i"...



Fuzeon Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Last reviewed on RxList 12/8/2015

Fuzeon (enfuvirtide) is a type of antiviral medication called a fusion inhibitor used to treat HIV, which causes acquired immunodeficiency syndrome (AIDS), and is usually given after other medications have been tried without successful treatment of HIV. Fuzeon is not a cure for HIV or AIDS. Common side effects of Fuzeon include pain, irritation, redness, itching, bruising, swelling, hardened skin, or bumps at the injection site. These types of reactions are common and may last up to 7 days. Other side effects of Fuzeon include runny or stuffy nose, constipation, pain or numbness in your feet or legs, tired feeling, muscle weakness or loss of strength, muscle pain, sleep problems (insomnia), or depression.

The recommended dose of Fuzeon is 90 mg (1 mL) twice daily injected subcutaneously into the upper arm, anterior thigh or abdomen. Fuzeon may interact with blood thinners. Tell your doctor all medications and supplements you use. Fuzeon should be used only when prescribed during pregnancy. It is unknown if this drug passes into breast milk. Because breast milk can transmit HIV, do not breastfeed.

Our Fuzeon (enfuvirtide) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Patient Information in Detail?

Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.

Fuzeon in Detail - Patient Information: Side Effects

Get emergency medical help if you have any of these signs of an allergic reaction: skin rash or hives; fever with vomiting; blood in your urine; difficulty breathing; fainting; swelling of your feet, face, lips, tongue, or throat.

Stop using enfuvirtide and call your doctor at once if you have any of these serious side effects:

  • fever, chills, chest congestion, cough with yellow or green mucus, stabbing chest pain, wheezing, feeling short of breath;
  • signs of a new infection such as sore throat, flu symptoms, swollen glands, easy bruising or bleeding (bleeding from your nose or gums), loss of appetite, mouth sores;
  • severe pain in your upper stomach spreading to your back, nausea and vomiting;
  • rapid heart rate, increased sweating, tremors, feeling anxious or irritable;
  • diarrhea, unexplained weight loss, menstrual changes, impotence, loss of interest in sex;
  • swelling in your neck or throat (enlarged thyroid);
  • problems with balance or eye movement, trouble speaking or swallowing;
  • severe lower back pain, loss of bladder or bowel control;
  • weakness or prickly feeling in your fingers or toes, tingling or nerve pain lasting for several weeks or months; or
  • pain, warmth, swelling, oozing, or redness where an injection was given, especially if these symptoms get worse or last longer than 7 days.

Less serious side effects may include:

  • constipation;
  • itching, irritation, mild redness, mild swelling, or raised bumps under your skin where the medicine was injected;
  • pain or numbness in your feet or legs;
  • tired feeling, muscle weakness or loss of strength;
  • muscle pain;
  • runny or stuffy nose;
  • sleep problems (insomnia); or
  • depression.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Fuzeon (Enfuvirtide)

What is Patient Information Overview?

A concise overview of the drug for the patient or caregiver from First DataBank.

Fuzeon Overview - Patient Information: Side Effects

SIDE EFFECTS: Pain, redness, itching, bruising, hardened skin, or bumps at the injection site may occur. These types of reactions are common and may last up to 7 days. Runny nose may also occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Some people may experience worsening of a previous medical condition (such as an old infection) as their immune systems improve, or develop new conditions because their immune systems have become overactive. This reaction may occur at any time (soon after starting HIV treatment or many months later). Tell your doctor right away if you have any serious side effects, including: unexplained weight loss, persistent muscle aches/weakness, joint pain, numbness/tingling of the hands/feet/arms/legs, severe tiredness, vision changes, severe/persistent headaches, signs of infection (such as fever, chills, trouble breathing, cough, non-healing skin sores), signs of an overactive thyroid (such as irritability, nervousness, heat intolerance, fast/pounding/irregular heartbeat, bulging eyes, unusual growth in the neck/thyroid known as a goiter), signs of a certain nerve problem known as Guillain-Barre Syndrome (such as difficulty breathing/swallowing/moving your eyes, drooping face, paralysis, slurred speech).

Tell your doctor right away if you have any serious side effects, including: anxiety, numbness/tingling/shooting nerve pain near injection site, signs of injection site infection (such as oozing, warmth, persistent pain and redness), abdominal pain, loss of appetite.

An allergic reaction to this drug is unlikely, but get medical help right away if it occurs. Symptoms of an allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing, fever, chills, nausea/vomiting.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the entire patient information overview for Fuzeon (Enfuvirtide)

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Fuzeon FDA Prescribing Information: Side Effects
(Adverse Reactions)


The following adverse reactions are discussed in greater detail in other sections:

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The overall safety profile of FUZEON is based on 2131 subjects who received at least 1 dose of FUZEON during various clinical trials. This includes 2051 adults, 658 of whom received the recommended dose for greater than 48 weeks, and 63 pediatric subjects.

Assessment of treatment-emergent adverse events is based on the pooled data from the two randomized, controlled, open-label, multicenter trials in treatment-experienced subjects, T20-301 (TORO 1) and T20-302 (TORO 2).

Local Injection Site Reactions

Local injection site reactions were the most frequent adverse events associated with the use of FUZEON. In T20-301 and T20-302, 98% of subjects had at least one local injection site reaction (ISR). A total of 7% of subjects discontinued treatment with FUZEON because of ISRs (4%) or difficulties with injecting FUZEON (3%) such as injection fatigue and inconvenience. Eighty-five percent of subjects experienced their first ISR during the initial week of treatment; ISRs continued to occur throughout treatment with FUZEON. For most subjects the severity of signs and symptoms associated with ISRs did not change during the 48 weeks of treatment. The majority of ISRs were associated with erythema, induration, the presence of nodules or cysts, and mild to moderate pain at the injection site (Table 2). In addition, the average duration of individual ISRs was between three and seven days in 41% of subjects and more than seven days in 24% of subjects. Also, the numbers of ISRs per subject at any one time was between six to 14 ISRs in 26% of subjects and more than ISRs in 1.3% of subjects. Infection at the injection site (including abscess and cellulitis) was reported in 1.7% of adult subjects.

Table 2 :Summary of Individual Signs/Symptoms Characterizing Local Injection Site Reactions to Enfuvirtide in Studies T20-301 and T20-302 Combined (% of Subjects) Through 48 Weeks

Event Category N=663
Any Severity Grade % of Subjects with Grade 3 Reactions % of Subjects with Grade 4 Reactions
Pain/Discomforta 96% 11% 0%
Induration 90% 39%
> 25 but < 50 mm
≥ 50 mm
Erythema 91% 22%
> 50 but < 85 mm
≥ 85 mm
Nodules and Cysts 80% 23%
> 3 cm average diameter
0.2% Draining
Pruritusb 65% 3% NA
Ecchymosis 52% 5%
> 3 but ≤ 5 cm
> 5 cm
aGrade 3 = severe pain requiring prescription non-topical analgesics or limiting usual activities. Grade 4 = severe pain requiring hospitalization or prolongation of hospitalization, resulting in death, or persistent or significant disability/incapacity, or life-threatening, or medically significant.
bGrade 3 = refractory to topical treatment or requiring oral or parenteral treatment. Grade 4 = not applicable.

Other Adverse Events

In T20-301 and T20-302, after study week 8, subjects on background alone who met protocol defined criteria for virological failure were permitted to revise their background regimens and add FUZEON. Exposure on FUZEON+background was 557 patient-years, and to background alone 162 patient-years. Due to this difference in exposure, safety results are expressed as the number of patients with an adverse event per 100 patient-years of exposure. For FUZEON+background, adverse events are also displayed by percent of subjects.

The events most frequently reported in subjects receiving FUZEON+background regimen, excluding ISRs, were diarrhea (38 per 100 patient-years or 31.7%), nausea (27 per 100 patient-years or 22.8%), and fatigue (24 per 100 patient-years or 20.2%). These events were also commonly observed in subjects that received background regimen alone: diarrhea (73 per 100 patient-years), nausea (50 per 100 patient-years), and fatigue (38 per 100 patient-years).

Treatment-emergent adverse events, regardless of causality and excluding ISRs, from Phase 3 studies are summarized for adult subjects, in Table 3. Any Grade 2 or above events occurring at ≥ 2 percent of subjects and at a higher rate in subjects treated with FUZEON are summarized in Table 3; events that occurred at a higher rate in the control arms are not displayed.

Rates of adverse events for subjects who switched to FUZEON after virological failure were similar.

Table 3 :Rates of Treatment-Emergent Adverse Events* ( ≥ Grade 2) Reported in ≥ 2% of Subjects Treated with FUZEON** (Pooled Studies T20-301/T20-302 at 48 Weeks)

Adverse Event (by System Organ Class) FUZEON+ Background Regimen
FUZEON+ Background Regimen
Background Regimen
663 subjects total 557 total patient-years 162 total patient-years
% frequency rate/100 patient-years rate/100 patient-years
Weight Decreased 6.6% 7.9 6.2
Sinusitis 6.0% 7.2 4.9
Abdominal Pain 3.9% 4.7 3.7
Cough 3.9% 4.7 2.5
Herpes Simplex 3.5% 4.1 3.7
Appetite Decreased 3.2% 3.8 2.5
Pancreatitis 3.0% 3.6 2.5
Pain in Limb 2.9% 3.4 3.1
Pneumonia (see text below) 2.7% 3.2 0.6
Myalgia 2.7% 3.2 1.2
Influenza-Like Illness 2.4% 2.9 1.9
Folliculitis 2.4% 2.9 2.5
Anorexia 2.3% 2.7 1.9
Dry Mouth 2.1% 2.5 1.9
Conjunctivitis 2.0% 2.3 1.9
*Excludes Injection Site Reactions
**Events listed occurred more frequently in subjects treated with FUZEON (based on rates/100 patient-years).

Less Common Events

The following adverse events have been reported in 1 or more subjects; however, a causal relationship to FUZEON has not been established.

Immune System Disorders: worsening abacavir hypersensitivity reaction

Renal and Urinary Disorders: glomerulonephritis; tubular necrosis; renal insufficiency; renal failure (including fatal cases)

Blood and Lymphatic Disorders: thrombocytopenia; neutropenia; fever; lymphadenopathy

Endocrine and Metabolic: hyperglycemia

Infections: sepsis; herpes simplex

Nervous System Disorders: taste disturbance; Guillain-Barre syndrome (fatal); sixth nerve palsy; peripheral neuropathy

Cardiac Disorders: unstable angina pectoris

Gastrointestinal Disorders: constipation; abdominal pain upper

General: asthenia

Hepatobiliary Disorders: toxic hepatitis; hepatic steatosis

Investigations: increased amylase; increased lipase; increased AST; increased GGT; increased triglycerides

Psychiatric Disorders: insomnia; depression; anxiety; suicide attempt

Respiratory, Thoracic, and Mediastinal Disorders: pneumopathy; respiratory distress; cough

Skin and Subcutaneous Tissue Disorders: pruritus

Laboratory Abnormalities

Table 4 shows the treatment-emergent laboratory abnormalities that occurred in at least 2 subjects per 100 patient-years and more frequently in those receiving FUZEON+background regimen than background regimen alone from T20-301 and T20-302.

Table 4 :Treatment-Emergent Laboratory Abnormalities in ≥ 2% of Subjects Receiving FUZEON* (Pooled Studies T20-301 and T20-302 at 48 Weeks)

Laboratory Parameters Grading FUZEON+ Background Regimen
FUZEON+ Background Regimen
Background Regimen
663 subjects total 557 total patient-years 162 total patient-years
% frequency rate/100 patient-years rate/100 patient-years
  1-2 X ULN (0.7 x 109/L) 0.7-1.4 x 109/L 9.1% 10.8 3.7
   > 2 X ULN (0.7 x 109/L) > 1.4 x 109/L 1.8% 2.2 1.8
  Grade 3 > 5-10 x ULN 4.1% 4.8 4.3
  Grade 4 > 10 x ULN 1.2% 1.4 1.2
Creatine Phosphokinase (U/L)
  Grade 3 > 5-10 x ULN 6.9% 8.3 8.0
  Grade 4 > 10 x ULN 2.6% 3.1 8.6
*Events listed occurred more frequently in subjects treated with FUZEON (based on rates/100 patient-years).

Adverse Events in Pediatric Patients

FUZEON has been studied in 63 pediatric subjects 5 through 16 years of age with duration of FUZEON exposure ranging from 1 dose to 134 weeks. Adverse experiences seen during clinical trials were similar to those observed in adult subjects, although infections at site of injection (cellulitis or abscess) were more frequent in adolescents than in adults, with 4 events occurring in 3 of 28 (11%) subjects.

Read the entire FDA prescribing information for Fuzeon (Enfuvirtide)

Fuzeon - User Reviews

Fuzeon User Reviews

Now you can gain knowledge and insight about a drug treatment with Patient Discussions.

Here is a collection of user reviews for the medication Fuzeon sorted by most helpful. Patient Discussions FAQs

Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

WebMD Daily

Get breaking medical news.