Ontak Side Effects
Generic name: denileukin diftitox
Medically reviewed by Drugs.com. Last updated on Jun 23, 2025.
Note: This document provides detailed information about Ontak Side Effects associated with denileukin diftitox. Some dosage forms listed on this page may not apply specifically to the brand name Ontak.
Applies to denileukin diftitox: intravenous injectable, intravenous solution.
Important warnings
This medicine can cause some serious health issues
Intravenous route (solution)
Serious and fatal infusion reactions may occur; therefore, patients treated with denileukin diftitox must be managed in a facility equipped and staffed for cardiopulmonary resuscitation.
Treatment with denileukin diftitox should be immediately stopped and permanently discontinued after serious infusion reactions.
Capillary leak syndrome resulting in death may also occur.
Patients weight, edema, blood pressure and serum albumin levels should be monitored prior to and during denileukin diftitox treatment.
Patients should also be monitored for loss of visual acuity and color vision.
Precautions
It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.
This medicine may cause a serious side effect called an infusion reaction. This can be life-threatening and requires immediate medical attention. Tell your doctor or nurse right away if you have fever, chills, breathing problems, chest pain, fast or pounding heartbeat, hives, or rash after you receive the injection.
Call your doctor right away if you have dizziness, faintness, or lightheadedness when getting up from a lying or sitting position; rapid weight gain; or swelling of hands, ankles, feet, or lower legs. These may be symptoms of a rare but serious condition called capillary leak syndrome.
Check with your doctor right away if you have any vision changes (e.g., decrease in vision, loss of color vision) while you are using this medicine. Your doctor may want you to have your eyes checked by an eye doctor.
Serious side effects of Ontak
Along with its needed effects, denileukin diftitox (the active ingredient contained in Ontak) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor or nurse immediately if any of the following side effects occur while taking denileukin diftitox:
More common side effects
- back pain
- bloating or swelling of the face, arms, hands, lower legs, or feet
- blurred vision
- body aches or pain
- chest pain
- confusion
- cough
- difficulty with breathing
- difficulty with moving
- difficulty with swallowing
- dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
- ear congestion
- fast or irregular heartbeat
- feeling unusually cold
- fever or chills
- headache
- loss of appetite
- loss of strength or energy
- loss of voice
- muscle aching or cramping
- muscle pains or stiffness
- nasal congestion
- nausea
- pain in the joints and muscles
- rapid weight gain
- rash
- runny nose
- shivering
- shortness of breath
- sneezing
- sore throat
- sweating
- swollen joints
- tightness in the chest
- tingling of the hands or feet
- unusual tiredness or weakness
- unusual weight gain or loss
- vomiting
- warmth and flushing of the skin
- wheezing
Less common side effects
- abdominal pain, severe
- black, tarry stools
- blood in the urine or stools
- cloudy urine
- cough or hoarseness accompanied by fever or chills
- headache, severe
- loss of coordination
- lower back or side pain accompanied by fever or chills
- pain in the groin or leg
- painful or difficult urination accompanied by fever or chills
- pinpoint red spots on the skin
- slurring of speech
- sudden vision changes
- swelling or pain at the injection site
- unusual bleeding or bruising
- weakness of the arm and leg
Rare side effects
- dry, puffy skin
- increased heart rate
- weight gain
Other side effects of Ontak
Some side effects of denileukin diftitox may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.
Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Less common
- constipation
- indigestion
- numbness or tingling of the fingers, toes, or face
- runny nose
- trouble with sleeping
See also:
For healthcare professionals
Applies to denileukin diftitox: intravenous powder for injection, intravenous solution.
Other adverse events
- Very common (10% or more): Infusion reactions (up to 70.5%), pyrexia (up to 63.6%), rigors (up to 47.3%), fatigue (up to 46.7%), peripheral edema (up to 25.5%), asthenia (up to 18.2%), pain (up to 12.7%), chest pain (up to 12.7%)[Ref]
Cardiovascular
- Very common (10% or more): Capillary leak syndrome (up to 32.5%), hypotension (up to 16.4%)[Ref]
Ocular
- Common (1% to 10%): Visual changes (e.g., visual acuity loss)[Ref]
Dermatologic
Endocrine
- Postmarketing reports: Thyroid conditions (hyperthyroidism, thyroiditis, thyrotoxicosis, and hypothyroidism)
Gastrointestinal
- Very common (10% or more): Nausea (up to 60%), vomiting (up to 34.5%), diarrhea (up to 22.2%)[Ref]
Hepatic
- Very common (10% or more): Increased ALT or increased AST (up to 84%)[Ref]
Metabolic
Musculoskeletal
- Very common (10% or more): Myalgia (up to 20%), back pain (up to 18.2%), arthralgia (up to 15.6%)[Ref]
Nervous system
- Very common (10% or more): Headache (up to 28.9%), dizziness (up to 12.7%), dysgeusia (up to 10.9%)[Ref]
Respiratory
- Very common (10% or more): Cough (up to 20%), upper respiratory tract infection (up to 13.3%), dyspnea (up to 13.3%)[Ref]
References
1. (2001) "Product Information. Ontak (denileukin diftitox)." Ligand Pharmaceuticals
More about Ontak (denileukin diftitox)
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- Dosage information
- During pregnancy
- Drug class: miscellaneous antineoplastics
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Further information
Ontak side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.