Slideshows Images Quizzes


Last reviewed on RxList: 3/13/2017
Foscavir Side Effects Center

Last reviewed on RxList 03/13/2017

Foscavir (foscarnet sodium injection) is an antiviral medication used to treat cytomegalovirus (CMV) retinitis in people with AIDS. Foscavir is also used to treat herpes simplex virus (HSV) in people with a weak immune system, and is usually given for HSV after other antiviral medications have been tried unsuccessfully. Foscavir is available in generic form. Common side effects of Foscavir include:

  • nausea
  • vomiting
  • stomach pain
  • headache
  • diarrhea
  • dizziness
  • loss of appetite
  • increased sweating
  • anxiety
  • depression
  • cough
  • skin rash
  • vision problems
  • tiredness
  • joint or muscle pain, or
  • pain or swelling where the injection was given.

This medication is used in patients who use other medications, and it may be difficult to tell which side effects are caused by Foscavir. Tell your doctor if you have serious side effects of Foscavir including:

  • mental/mood changes,
  • new vision problems,
  • muscle cramps or spasms,
  • weakness,
  • fast breathing,
  • fast or irregular heartbeat,
  • unusual tiredness,
  • a change in the amount of urine,
  • painful urination,
  • irritation or sores on the penis,
  • vaginal irritation or sores,
  • seizures, or
  • signs of infection (such as fever, persistent sore throat).

The recommended initial dose of Foscavir for patients with normal renal function is: For CMV retinitis patients, either 90 mg/kg (1-1/2 to 2 hour infusion) every twelve hours or 60 mg/kg (minimum one hour infusion) every eight hours over 2-3 weeks depending on clinical response. For acyclovir-resistant HSV patients, 40 mg/kg (minimum one hour infusion) either every 8 or 12 hours for 2-3 weeks or until healed. Foscavir may interact with amphotericin B, cancer medications, digoxin, diuretics (water pills), laxatives, bowel stimulants, leucovorin, pentamidine, IV phenytoin, promethazine, IV sedatives, tacrolimus, trimethoprim, sulfamethoxazole, antibiotics, or antiviral medicines. Tell your doctor all medications and supplements you use. During pregnancy, Foscavir should be used only when prescribed. It is unknown if this drug passes into breast milk. Because of the possible harm to the infant, breastfeeding is not recommended.

Our Foscavir (foscarnet sodium injection) 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.

Foscavir Consumer Information

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

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

  • urinating less than usual or not at all;
  • drowsiness, confusion, mood changes, increased thirst, loss of appetite, nausea and vomiting;
  • swelling, weight gain, feeling short of breath;
  • numbness or tingling around your mouth or in your hands or feet;
  • dry mouth, increased thirst, restless feeling, increased urination, muscle pain or weakness, fainting, or seizure (convulsions);
  • fever, chills, body aches, flu symptoms;
  • pale skin, feeling light-headed, rapid heart rate, trouble concentrating; or
  • restless muscle movements in your eyes, tongue, jaw, or neck;
  • trouble breathing; or
  • pain or burning when you urinate.

Less serious side effects may include:

  • anxiety, depressed mood;
  • stomach pain;
  • headache, dizziness;
  • cough;
  • increased sweating;
  • skin rash;
  • problems with vision;
  • tired feeling;
  • joint or muscle pain; or
  • pain or swelling where the injection was given.

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 Foscavir (Foscarnet Sodium Injection)

Foscavir Professional Information


THE MAJOR TOXICITY OF FOSCAVIR IS RENAL IMPAIRMENT (see WARNINGS). Approximately 33% of 189 patients with AIDS and CMV retinitis who received FOSCAVIR (60 mg/kg TID), without adequate hydration, developed significant impairment of renal function (serum creatinine ≥ 2.0 mg/dL). The incidence of renal impairment in subsequent clinical trials in which 1000 mL of normal saline or 5% dextrose solution was given with each infusion of FOSCAVIR was 12% (34/280).

FOSCAVIR has been associated with changes in serum electrolytes including hypocalcemia (15–30%), hypophosphatemia (8–26%) and hyperphosphatemia (6%), hypomagnesemia (15– 30%), and hypokalemia (16–48%) (see WARNINGS). The higher percentages were derived from those patients receiving hydration.

FOSCAVIR treatment was associated with seizures in 18/189 (10%) AIDS patients in the initial five controlled studies (see WARNINGS). Risk factors associated with seizures included impaired baseline renal function, low total serum calcium, and underlying CNS conditions predisposing the patient to seizures. The rate of seizures did not increase with duration of treatment. Three cases were associated with overdoses of FOSCAVIR (see OVERDOSE).

In five controlled U.S. clinical trials the most frequently reported adverse events in patients with AIDS and CMV retinitis are shown in Table 9. These figures were calculated without reference to drug relationship or severity.

Adverse Events Reported in Five Controlled US Clinical Trials

  n = 189   n = 189
Fever 65% Abnormal Renal Function 27%
Nausea 47% Vomiting 26%
Anemia 33% Headache 26%
Diarrhea 30% Seizures 10%

From the same controlled studies, adverse events categorized by investigator as “severe” are shown in Table 10. Although death was specifically attributed to FOSCAVIR in only one case, other complications of FOSCAVIR (i.e., renal impairment, electrolyte abnormalities, and seizures) may have contributed to patient deaths (see WARNINGS).

Severe Adverse Events

  n = 189
Death 14%
Abnormal Renal Function 14%
Marrow Suppression 10%
Anemia 9%
Seizures 7%

From the five initial U.S. controlled trials of FOSCAVIR, the following list of adverse events has been compiled regardless of causal relationship to FOSCAVIR. Evaluation of these reports was difficult because of the diverse manifestations of the underlying disease and because most patients received numerous concomitant medications.

Incidence Of 5% Or Greater

Body as a Whole: fever, fatigue, rigors, asthenia, malaise, pain, infection, sepsis, death

Central and Peripheral Nervous System: headache, paresthesia, dizziness, involuntary muscle contractions, hypoesthesia, neuropathy, seizures including grand mal seizures (see WARNINGS)

Gastrointestinal System: anorexia, nausea, diarrhea, vomiting, abdominal pain

Hematologic: anemia, granulocytopenia, leukopenia, neutropenia (see PRECAUTIONS)

Metabolic and Nutritional: mineral and electrolyte imbalances (see WARNINGS) including hypokalemia, hypocalcemia, hypomagnesemia, hypophosphatemia, hyperphosphatemia

Psychiatric: depression, confusion, anxiety

Respiratory System: coughing, dyspnea

Skin and Appendages: rash, increased sweating

Urinary: alterations in renal function including increased serum creatinine, decreased creatinine clearance, and abnormal renal function (see WARNINGS)

Special Senses: vision abnormalities

Incidence Between 1% And 5%

Application Site: injection site pain, injection site inflammation

Body as a Whole: back pain, chest pain (including reports of transient chest pain as part of infusion reactions), edema, influenza-like symptoms, bacterial infections, moniliasis, fungal infections, abscess

Cardiovascular: hypertension, palpitations, ECG abnormalities including sinus tachycardia, first degree AV block and non-specific ST-T segment changes, hypotension, flushing, cerebrovascular disorder (see WARNINGS)

Central and Peripheral Nervous System: tremor, ataxia, dementia, stupor, generalized spasms, sensory disturbances, meningitis, aphasia, abnormal coordination, leg cramps, EEG abnormalities (see WARNINGS)

Gastrointestinal: constipation, dysphagia, dyspepsia, rectal hemorrhage, dry mouth, melena, flatulence, ulcerative stomatitis, pancreatitis

Hematologic: thrombocytopenia, platelet abnormalities, thrombosis, white blood cell abnormalities, lymphadenopathy

Liver and Biliary: abnormal A-G ratio, abnormal hepatic function, increased SGPT, increased SGOT

Metabolic and Nutritional: hyponatremia, decreased weight, increased alkaline phosphatase, increased LDH, increased BUN, acidosis, cachexia, thirst

Musculo-Skeletal:arthralgia, myalgia

Neoplasms: lymphoma-like disorder, sarcoma

Psychiatric: insomnia, somnolence, nervousness, amnesia, agitation, aggressive reaction, hallucination

Respiratory System: pneumonia, sinusitis, pharyngitis, rhinitis, respiratory disorders, respiratory insufficiency, pulmonary infiltration, stridor, pneumothorax, hemoptysis, bronchospasm Skin and

Appendages: pruritus, skin ulceration, seborrhea, erythematous rash, maculopapular rash, skin discoloration

Special Senses: taste perversions, eye abnormalities, eye pain, conjunctivitis

Urinary System:albuminuria, dysuria, polyuria, urethral disorder, urinary retention, urinary tract infections, acute renal failure, nocturia, facial edema

Selected adverse events occurring at a rate of less than 1% in the five initial U.S. controlled clinical trials of FOSCAVIR include: syndrome of inappropriate antidiuretic hormone secretion, pancytopenia, hematuria, dehydration, hypoproteinemia, increases in amylase and creatinine phosphokinase, cardiac arrest, coma, and other cardiovascular and neurologic complications.

Selected adverse event data from the Foscarnet vs. Ganciclovir CMV Retinitis Trial (FGCRT), performed by the Studies of the Ocular Complications of AIDS (SOCA) Research Group, are shown in Table 11 (see Clinical Trials).

FGRCT: Selected Adverse Events*

No. of
Rates No. of
Absolute neutrophil count decreasing to <0.50 x 109 per liter 63 41 1.30 31 17 0.72
Serum creatinine increasing to >260 µmol per liter (>2.9 mg/dL) 6 4 0.12 13 9 0.30
Seizure 21 13 0.37 19 13 0.37
Catheterization-related infection 49 27 1.26 51 28 1.46
Hospitalization 209 91 4.74 202 75 5.03
* Values for the treatment groups refer only to patients who completed at least one follow-up visit – i.e., 133 to 119 patientsin the ganciclovir group and 93 to 100 in the foscarnet group. “Events” denotes all events observed and “patients” the numberof patients with one or more of the indicated events.
Per person-year at risk
Final frozen SOCA I database dated October 1991

Selected adverse events from ACTG Study 228 (CRRT) comparing combination therapy with FOSCAVIR or ganciclovir monotherapy are shown in Table 12. The most common reason for a treatment change in patients assigned to either FOSCAVIR or ganciclovir was retinitis progression. The most frequent reason for a treatment change in the combination treatment group was toxicity.

CRRT: Selected Adverse Events

Rate No.
Rate No.
Anemia (Hgb <70g/L) 11 7 0.20 9 7 0.14 19 15 0.33
  ANC <0.75 x 109 cells/L 86 32 1.53 95 41 1.51 107 51 1.91
  ANC <0.50 x 109 cells/L 50 25 0.91 49 28 0.80 50 28 0.85
  Platelets <50 x 109/L 28 14 0.50 19 8 0.43 40 15 0.56
  Platelets <20 x 109/L 1 1 0.01 6 2 0.05 7 6 0.18
  Creatinine >260 μmol/L (>2.9 mg/dL) 9 7 0.15 10 7 0.17 11 10 0.20
Seizures 6 6 0.17 7 6 0.15 10 5 0.18
Hospitalizations 86 53 1.86 111 59 2.36 118 64 2.36
* Pts. = patients with event;
Rate = events/person/year;
ANC = absolute neutrophil count

Adverse events that have been reported in post-marketing surveillance include: administration site extravasation, localized edema, hypersensitivity reactions (including anaphylactic shock, urticaria and angioedema) (see WARNINGS), gastrointestinal hemorrhage, increased lipase, glomerulonephritis, nephrotic syndrome, proteinuria, status epilepticus, ventricular arrhythmia, prolongation of QT interval, torsade de pointes (see WARNINGS), gamma GT increased, diabetes insipidus (usually nephrogenic), renal calculus, Fanconi syndrome acquired, renal tubular acidosis, renal tubular necrosis, crystal-induced nephropathy, hypercalcemia, hypernatremia, esophageal ulceration and muscle disorders including myopathy, myositis, muscle weakness and rare cases of rhabdomyolysis. Cases of vesiculobullous eruptions including erythema multiforme, toxic epidermal necrolysis, and Stevens-Johnson syndrome have been reported. In most cases, patients were taking other medications that have been associated with toxic epidermal necrolysis or Stevens-Johnson syndrome.

Read the entire FDA prescribing information for Foscavir (Foscarnet Sodium Injection)

Related Resources for Foscavir

© Foscavir Patient Information is supplied by Cerner Multum, Inc. and Foscavir Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

Health Solutions From Our Sponsors