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Denileukin Diftitox Injection

Denileukin diftitox (LYMPHIR) is a targeted cancer therapy used to treat a type of skin lymphoma that has returned or stopped responding to prior treatment.

Brand names OntakLymphir
Drug class Cd25-directed Cytotoxin
Rx Form 1
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026 Content updated Oct 7, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

✓No current FDA shortage listed · checked Oct 7, 2026
Denileukin Diftitox Injection at a glance The quick version — the full detail is in the Patient Information Guide below.
Dr. Brian Staiger, PharmD, BCPS
The Pharmacist’s Take By · Clinical pharmacist · Written

Denileukin diftitox (Lymphir, first marketed as Ontak around 1999, not available generically) is a specialist IV drug for cutaneous T-cell lymphoma (a skin lymphoma) that has come back after earlier whole-body treatment; it latches onto the IL-2 receptor on the cancerous T cells and releases a modified diphtheria toxin that kills them. Side effects are common, mostly nausea, tiredness, swelling, chills and fever, plus higher liver enzymes on blood work. The one to watch is the boxed warning for capillary leak syndrome (fluid leaking out of blood vessels), which can crash blood pressure and has been fatal, so report sudden swelling, dizziness or feeling faint right away.

Clinical pearls

  • Albumin, a blood protein, is checked before every cycle, and a low level means the next round is delayed.
  • Expect pre-medications before each infusion, especially in the first three cycles, to lower the risk of infusion reactions.
  • Any blurry or worsening vision during treatment needs a prompt eye check, not a wait until the next cycle.
  • Use effective contraception and avoid breastfeeding during treatment and for 7 days after the last dose.
How we write & review this content — our editorial policy →
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾

LYMPHIR carries a boxed warning — the FDA's most serious safety alert — for capillary leak syndrome (CLS). CLS is a condition where fluid escapes from your blood vessels into body tissues. It can cause severe swelling, a dangerous drop in blood pressure, and very low levels of albumin (a key blood protein). In some cases, CLS has been life-threatening or fatal. This can happen at any point during treatment. Your medical team will watch for signs like sudden swelling, lightheadedness, or low blood pressure, and will hold or stop treatment depending on how serious it is. Report any of these symptoms to your care team immediately.

Read the full warning on DailyMed →
How you get itPrescription only
Comes asInjection
Earliest FDA record1999
FDA label last updatedJan 23, 2025
FDA’s strongest warning (boxed)Yes, read the warning

Patient information guide A plain-language walkthrough of Denileukin Diftitox Injection, written from its FDA label.

What Denileukin Diftitox Injection is used for

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LYMPHIR treats a type of blood cancer that primarily affects the skin. It is approved for adults with:

  • Relapsed or refractory cutaneous T-cell lymphoma (CTCL) — specifically Stage I, II, or III disease
  • Patients who have already received at least one prior systemic (whole-body) therapy

How Denileukin Diftitox Injection works

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LYMPHIR is engineered as a fusion protein — two functional parts joined together. The first part targets the IL-2 receptor, a protein found on the surface of the abnormal T-cells responsible for CTCL. The second part is a modified diphtheria toxin. When LYMPHIR binds to an IL-2 receptor-bearing cell and gets pulled inside, the toxin is released, blocks the cell's ability to make proteins, and kills it. It also works to deplete regulatory T cells (Tregs) — immune cells that can shield tumors from the body's natural defenses.

Denileukin Diftitox Injection dosage

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LYMPHIR is given as an IV infusion in a clinical or hospital setting — not taken at home. It is infused once daily over 60 minutes on Days 1 through 5 of a 21-day cycle, then you have about 16 days off before the next cycle begins. Treatment continues until the disease progresses or side effects become unacceptable.

  • Pre-medications (to reduce infusion reactions) are given at least 30 minutes before each infusion, especially in the first three cycles
  • Your albumin level and liver and kidney function will be checked before each cycle starts
  • If your albumin is too low, your care team will delay the next cycle until it recovers

Dosing details from the FDA-approved label

From the Denileukin Diftitox Injection prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.

Delay start of treatment cycle if serum albumin level is below 3 g/dL.

Read the label’s full dosing text

2 DOSAGE AND ADMINISTRATION Delay start of treatment cycle if serum albumin level is below 3 g/dL. ( 2.1 ) The recommended dosage of LYMPHIR is 9 mcg/kg/day actual body weight administered as an intravenous infusion on Days 1 through 5 of a 21-day cycle. ( 2.2 ) Administer premedication as recommended. ( 2.3 ) See full prescribing information for preparation and administration instructions. ( 2.5 ) 2.1 Important Dosing Instructions Prior to starting each treatment cycle, assess hepatic and renal function. If serum albumin is less than 3 g/dL, delay administration of LYMPHIR until serum albumin is greater than or equal to 3 g/dL [see Warnings and Precautions ( 5.1 )] . 2.2 Recommended Dosage The recommended dosage of LYMPHIR is 9 mcg/kg/day actual body weight administered as an intravenous infusion over 60 minutes on Days 1 through 5 of a 21-day treatment cycle. Administer LYMPHIR until disease progression or unacceptable toxicity. 2.3 Recommended Premedications Administer premedications prior to starting a LYMPHIR infusion in Cycles 1 through 3, as outlined in Table 1, to reduce the risk of infusion-related reactions [see Warnings and Precautions ( 5.3 )] . Table 1. Premedication to be Administered to Patients Prior to LYMPHIR Infusion Treatment Cycle Premedication Dosage Administration Cycles 1-3 (optional thereafter) Antipyretic Oral acetaminophen 650 mg or per local institutional guidelines At least 30 minutes prior to infusion Antihistamine Diphenhydramine 25 mg intravenously or other antihistamine per local institutional guidelines At least 30 minutes prior to infusion Antiemetic Per institutional guidelines At least 30 minutes prior to infusion Hydration 250 to 500 mL 0.9% Sodium Chloride Injection intravenously (or other amount of fluid considered to be most appropriate for the subject’s condition) At least 30 minutes prior to infusion If patients experience a Grade 2 or higher infusion reaction, premedicate at least 30 minutes prior to each subsequent infusion with a systemic steroid such as dexamethasone 4 mg (or equivalent) via slow intravenous push, for at least 3 cycles. 2.4 Dosage Modifications for Adverse Reactions Dosage modifications for adverse reactions with LYMPHIR are shown in Table 2 below.

Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →

Denileukin Diftitox Injection side effects

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The most common side effects reported in clinical trials include:

Common side effects

  • Elevated liver enzymes (sign of liver stress)
  • Low albumin (a blood protein) levels
  • Nausea
  • Swelling (edema)
  • Low hemoglobin (anemia)
  • Fatigue
  • Muscle and bone pain
  • Rash, chills, fever, or constipation

When to get medical help

  • Signs of capillary leak syndrome: sudden swelling, low blood pressure, or feeling faint — seek medical help right away
  • Vision changes or worsening eyesight during treatment
  • Severe infusion reactions during or after the IV drip: chest tightness, difficulty breathing, or rapid heart rate
  • Signs of liver problems: yellowing of the skin or eyes, dark urine, or severe upper abdominal pain
  • If you are pregnant or think you may be pregnant — this drug can harm a developing baby

More serious reactions — including capillary leak syndrome, liver toxicity, vision changes, and infusion reactions — require prompt medical attention. Contact your care team right away if any of these develop.

Denileukin Diftitox Injection warnings and precautions

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  • Capillary leak syndrome (CLS): The most serious risk. Fluid leaks from blood vessels, causing swelling, low blood pressure, and low albumin. Can be life-threatening. Treatment may be paused or permanently stopped based on severity.
  • Vision changes: Some patients experience visual impairment during treatment. Your care team will monitor your eyesight and may hold or discontinue treatment if problems arise.
  • Infusion-related reactions: Reactions during the IV infusion can occur. Pre-medications are given to reduce this risk, and the infusion may be slowed or stopped if a reaction happens.
  • Liver toxicity (hepatotoxicity): Liver enzymes and bilirubin (a liver marker) are checked at baseline and throughout treatment. Higher drug exposure increases this risk.
  • Fetal harm: LYMPHIR can harm a developing baby. Women of childbearing potential must use effective contraception during treatment and for 7 days after the last dose.

Denileukin Diftitox Injection interactions

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The FDA label for LYMPHIR does not identify specific drug, food, or supplement interactions at this time. Always tell your entire care team — including your pharmacist — about every medication, supplement, and herbal product you take.

  • No specific interactions are listed in the current prescribing information

Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.

🌿17 supplements and herbs with documented Denileukin Diftitox Injection interactions, ranked by severity Check Denileukin Diftitox Injection against a supplement or herb →

Before taking Denileukin Diftitox Injection

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  • Pregnancy: This drug can harm a fetus. A pregnancy test is required before starting, and effective contraception must be used during treatment and for 7 days after the last dose.
  • Breastfeeding: Do not breastfeed during treatment or for 7 days after the last dose — the drug's effects on a nursing infant are unknown.
  • Male fertility: Animal studies suggest LYMPHIR may affect male fertility; whether this is reversible is unknown. Discuss this with your doctor before starting.
  • Children: Safety and effectiveness in patients under 18 have not been established.
  • Older adults: About half of patients in the main clinical trial were 65 or older; no clear difference in response was identified, but clinical data were limited.
  • Liver or kidney impairment: Mild impairment does not significantly change how the drug behaves, but moderate-to-severe hepatic impairment or severe renal impairment have not been fully studied.
  • Low albumin: Treatment will be delayed if your blood albumin is below 3 g/dL at the start of a cycle.

What Denileukin Diftitox Injection does in the body

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Higher levels of LYMPHIR in the blood are linked to a greater chance of serious side effects — including capillary leak syndrome, liver toxicity, severe adverse reactions, and treatment discontinuation. In other words, more drug exposure means more risk, which is why dosing and monitoring are carefully managed. The exact time course of how and when the drug produces its effects in the body is not fully known.

How your body processes Denileukin Diftitox Injection

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LYMPHIR is given as a one-hour IV infusion and reaches peak blood levels relatively quickly. Its half-life — the time it takes for half the drug to clear from your body — is about 112 minutes (roughly under 2 hours). It does not build up in the body with repeated daily dosing over the 5-day cycle. The drug is broken down (metabolized) into small peptides through normal body processes and is cleared from the body at a predictable rate. Age, weight, sex, race, and mild-to-moderate kidney or liver problems do not appear to meaningfully change how the body handles it.

How to store Denileukin Diftitox Injection

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Store LYMPHIR in a refrigerator between 2°C to 8°C (36°F to 46°F) in the original carton to protect from light. Do not freeze.

Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →

17

Supplements & herbs that interact with Denileukin Diftitox Injection

17 supplements and herbal products have documented interactions with Denileukin Diftitox Injection in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.

Severity mix
  • Major · 1
  • Moderate · 7
  • Minor · 9
ACTIVATED CHARCOAL Major COFFEE CHARCOAL Moderate EUROPEAN MANDRAKE Moderate GLUCOMANNAN Moderate GUAR GUM Moderate GUM ARABIC Moderate SLIPPERY ELM Moderate TRAGACANTH Moderate +9 more
Every supplement checked against Denileukin Diftitox Injection — ranked by severity The full interaction hub: 1 major · 7 moderate · 9 minor · every one linked to its full report. Check Denileukin Diftitox Injection against your exact supplements

Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.

Denileukin Diftitox Injection: pharmacist answers to common questions

Quick, plain-English answers to the questions patients ask most about Denileukin Diftitox Injection — the kind of thing our pharmacy team would talk through with you at the counter.

What exactly is this drug treating, and why was I given it instead of something else?

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LYMPHIR targets a specific type of skin lymphoma called cutaneous T-cell lymphoma (CTCL) — a cancer that starts in immune cells and shows up mainly on the skin. It's used when the disease has come back or stopped responding after at least one earlier systemic treatment. Your oncologist chose it because it's specifically designed to seek out and destroy the type of cancer cells involved in CTCL, using a precision-guided approach that other treatments don't use.

How is this given — do I take it at home?

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No, LYMPHIR is given by IV infusion in a clinic or infusion center — not at home as a pill or injection you self-administer. You'll come in for 5 consecutive days, receive a 60-minute infusion each day, and then have about 16 days off before the next round begins. Before each infusion, you'll also receive pre-medications to help prevent reactions, especially in the first three cycles.

What side effects should I just expect versus which ones mean I need to call someone right away?

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Common things many patients notice include nausea, fatigue, muscle aches, chills, rash, and some swelling — these are worth telling your team about but are generally manageable. What you need to act on immediately is sudden or worsening swelling, feeling lightheaded or having low blood pressure, or any changes to your vision. These could be signs of a serious condition called capillary leak syndrome or other significant complications, and your care team needs to know right away.

I've heard there's a really serious warning with this drug — what should I know?

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Yes, and it's worth taking seriously. The biggest concern is something called capillary leak syndrome, where fluid escapes from the blood vessels into your body's tissues. It can cause dangerous drops in blood pressure, significant swelling, and low protein levels in your blood. In some cases it has been life-threatening. Your care team will monitor you closely at every visit, and treatment will be paused or stopped if this develops. The key is to report any sudden swelling or dizziness right away — don't wait for your next appointment.

Can I get pregnant or breastfeed while on this treatment?

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No — this is really important. LYMPHIR can harm a developing baby, so you should not become pregnant during treatment. If you could become pregnant, effective contraception is required during the entire treatment period and for 7 days after your last dose. Breastfeeding is also not recommended during treatment or for 7 days after the last dose. Your team will check a pregnancy test before you start. If you have any concerns about fertility or family planning, please bring them up before treatment begins.

Will my liver and kidneys be checked while I'm on this?

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Yes — your care team will check your liver enzymes, bilirubin, albumin, and kidney function before every treatment cycle. This is a routine and important part of your care with LYMPHIR, because the drug can affect liver function, and low albumin levels are a signal to delay the next cycle. Think of these lab checks as built-in safety checkpoints — they help your team catch any issues early and adjust your treatment if needed.

Is Denileukin Diftitox Injection available over the counter?

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No. Denileukin Diftitox Injection is a prescription medicine: every Denileukin Diftitox Injection product listed with the FDA is prescription only, so it is not sold over the counter. Your prescriber decides whether it is appropriate for you, and your pharmacist dispenses it.

When was Denileukin Diftitox Injection first available?

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The earliest FDA record we hold for Denileukin Diftitox Injection is from 1999: its first approval in Drugs@FDA or its earliest product listing in the NDC Directory, whichever is older. Many older medicines were in use before their first formal FDA approval, so this is the earliest date on record, not necessarily when Denileukin Diftitox Injection was first used.

Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →

More about Denileukin Diftitox Injection on HelloPharmacist

📊Denileukin Diftitox Injection supplement interactions17 checked — ranked by severity 🌿Drug & Supplement CheckerDenileukin Diftitox Injection vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Denileukin Diftitox Injection NDCs & costs 🅰️Browse Drugs A–ZLook up any medication
Detailed data & references for Denileukin Diftitox Injection Forms & strengths, pricing, billing codes, manufacturers, safety reports and sourcing — the data behind the page. Most people can stop here. Each section below opens on a tap.

Denileukin Diftitox Injection forms and strengths (how it comes)

Denileukin Diftitox Injection is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Need a version that does not list lactose, a gluten source, a dye or gelatin? Inactive ingredients differ by manufacturer: see Denileukin Diftitox Injection inactive ingredients by manufacturer.

Injection

By injection
Available strengths 1 strength
150 mcg/mL
1 FDA-listed product record ⓘ

Denileukin Diftitox Injection on the U.S. market: products, makers and brands

How Denileukin Diftitox Injection appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

The FDA lists Denileukin Diftitox Injection products, mostly as injection; the earliest marketing or approval year on record is 1999. Brand names on the directory include Ontak, Lymphir; the rest are generics.

1
Dose forms ⓘ
1999
Earliest FDA record ⓘ

Denileukin Diftitox Injection recall history

A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.

The FDA’s enforcement reports list no Denileukin Diftitox recalls since July 2021.

✅No Denileukin Diftitox recalls on record since July 2021

Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Denileukin Diftitox Injection RxCUI 214470 1 dose form · 1 strength
  1. Dose form (SCDF) Injection RxCUI 1807475 In current FDA listings
    Clinical drug / strength (SCD) cxdl 0.3 MG RxCUI 2700750

Look up RxCUI 214470 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

Denileukin Diftitox Injection brand names

Denileukin Diftitox Injection is sold under 2 brand names in the FDA directory — Ontak, Lymphir. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.

Ontak Lymphir

Denileukin Diftitox Injection drug class (RxNorm)

Denileukin Diftitox Injection belongs to the CD25-directed Cytotoxin class.

Pharmacologic class CD25-directed Cytotoxin
Drug family (ATC) Other antineoplastic agents

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

Sources for this Denileukin Diftitox Injection page

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Jan 23, 2025
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Denileukin Diftitox Injection.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Denileukin Diftitox Injection after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
1
Linked representative label ⓘ
Citius Pharmaceuticals, Inc.
Linked label effective
Jan 23, 2025
Composite sections available
20
Linked SPL Set ID
ac3613d7-4304-40e7-a3f5-adb8a8adca5d
Linked SPL Document ID
2c678496-2a12-3051-e063-6294a90a205e
Open the linked representative label on DailyMed ↗

How this page is built

HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Citius Pharmaceuticals, Inc. is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →