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Ontak Side Effects

Generic name: denileukin diftitox

Medically reviewed by Last updated on Jun 21, 2024.

Note: This document contains side effect information about denileukin diftitox. Some dosage forms listed on this page may not apply to the brand name Ontak.

Applies to denileukin diftitox: intravenous injectable, intravenous solution.


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.

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

Less common


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:

More common

Less common

For Healthcare Professionals

Applies to denileukin diftitox: intravenous solution.


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]


Very common (10% or more): Capillary leak syndrome (up to 32.5%), hypotension (up to 16.4%)[Ref]


Common (1% to 10%): Visual changes (e.g., visual acuity loss)[Ref]


Very common (10% or more): Rash (up to 24.4%), pruritus (up to 18.2%)[Ref]


Postmarketing reports: Thyroid conditions (hyperthyroidism, thyroiditis, thyrotoxicosis, and hypothyroidism)


Very common (10% or more): Nausea (up to 60%), vomiting (up to 34.5%), diarrhea (up to 22.2%)[Ref]


Very common (10% or more): Increased ALT or increased AST (up to 84%)[Ref]


Very common (10% or more): Anorexia (up to 20%)[Ref]


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]


Very common (10% or more): Cough (up to 20%), upper respiratory tract infection (up to 13.3%), dyspnea (up to 13.3%)[Ref]


1. (2001) "Product Information. Ontak (denileukin diftitox)." Ligand Pharmaceuticals

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.