Darzalex (daratumumab) — A Clear, Patient-Friendly Guide

Darzalex is a targeted cancer medicine used for multiple myeloma and, in a specific formulation, for newly diagnosed light chain (AL) amyloidosis. You’ll often see two versions: Darzalex (IV infusion) and Darzalex Faspro (a fixed-dose subcutaneous shot that combines daratumumab with hyaluronidase). In this guide, you’ll learn what Darzalex is, how it works, when it’s prescribed, how it’s given, possible side effects, safety tips, and plain-English answers to common questions (including cost, infusion vs injection, and lab test “gotchas”). FDA Access Data+1

Quick disclaimer: This article is for education only and isn’t medical advice. Always follow your oncology team’s instructions.

What Is Darzalex?

Darzalex is the brand name for daratumumab, a monoclonal antibody that targets CD38, a protein found at high levels on myeloma cells. It’s available in two prescription forms:

• Darzalex (IV infusion): daratumumab given into a vein on a weight-based schedule.
• Darzalex Faspro (subcutaneous): a fixed dose of daratumumab plus hyaluronidase (to help the medicine absorb under the skin) given as a quick abdominal injection. This formulation is also the one approved for newly diagnosed AL amyloidosis in combination with CyBorD. FDA Access Data+1

How Does Darzalex Work?

Daratumumab locks onto the CD38 protein and helps the immune system recognize and kill cancer cells. It can trigger cell death through several mechanisms (immune-mediated cell killing and direct apoptosis) and may also change the tumor microenvironment in ways that favor immune attack. Because CD38 is present on myeloma cells, blocking it can slow or stop the disease. FDA Access Data

Common Uses of Darzalex

Oncologists use Darzalex across the myeloma journey:

• Newly diagnosed multiple myeloma: Often combined with standard backbones (e.g., D-VRd, D-VMP, D-VTd) depending on transplant plans and regional guidelines.
• Relapsed/refractory multiple myeloma: Used alone or, more often, in combinations (e.g., D-Rd, D-Vd, D-Pd, D-Kd) tailored to prior therapies and patient factors.
• AL (light chain) amyloidosis: Darzalex Faspro with bortezomib, cyclophosphamide, and dexamethasone (CyBorD) for newly diagnosed adults. (Note: the amyloidosis indication applies to the subcutaneous product.) FDA Access DataEuropean Medicines Agency (EMA)

Dosage & Administration

Your exact regimen and schedule come from your oncology team and may differ based on the combination you receive.

Adults (Multiple Myeloma)

• Darzalex (IV): Typically 16 mg/kg with a “front-loaded” schedule (weekly, then every 2 weeks, then every 4 weeks) depending on the regimen. Infusions are lengthy at first and get faster over time if tolerated. Premedication is required. FDA Access Data
• Darzalex Faspro (SC): Fixed dose 1,800 mg daratumumab + 30,000 units hyaluronidase (15 mL) injected under the skin of the abdomen—usually over a few minutes. Dosing follows a similar step-down pattern (weekly → every 2–3 weeks → every 4 weeks) per the combination. Premedication is still required. FDA Access Data

Adults (AL Amyloidosis)

• Darzalex Faspro + CyBorD with a schedule that steps down from weekly to every 2 weeks and then every 4 weeks, as directed by your team. FDA Access Data

Pediatric use

• Safety and effectiveness in children have not been established for these indications. FDA Access Data

Premedications & After-meds (Why they matter)

Before each dose, patients receive medicines such as a corticosteroid, acetaminophen, and an H1 antihistamine to prevent infusion/injection reactions. Your team may also give post-dose steroids to reduce delayed reactions, and many patients are placed on antiviral prophylaxis to lower the risk of shingles (herpes zoster) reactivation. FDA Access Data

Step-by-Step Tips for a Smoother Visit

1. Bring your med list and mention allergies or past reactions.
2. Eat and hydrate unless told otherwise; plan for a longer first visit.
3. Tell the team about any infections (fever, cough, shingles-like rash) before treatment day.
4. Carry a transfusion alert card or written note that you’re on daratumumab (important for blood bank testing—see below). Official DARZALEX HCP Website

Side Effects of Darzalex

Most people tolerate therapy with supportive care, but side effects can happen. Always report symptoms promptly; your team can premedicate, slow/hold doses, or adjust other drugs.

Common:

• Administration reactions (during or after IV/SC dosing): nasal congestion, throat irritation, cough, chills, nausea, fever, shortness of breath, rash; most occur with the first dose.
• Blood count changes: lowered white cells, lymphocytes, neutrophils, and platelets; anemia.
• Fatigue, nausea, diarrhea/constipation, injection-site redness (SC). FDA Access Data

Less common but important:

• Infections (including shingles) — why antiviral prophylaxis is often used.
• Severe hypersensitivity or anaphylaxis (rare).
• Liver issues from hepatitis B reactivation in people with prior infection — screening and monitoring are essential. FDA Access Data+1

If something feels “not right,” call your clinic—especially breathing trouble, hives, facial swelling, high fever, or a new shingles-type rash.

Warnings & Precautions (Read This)

• Blood transfusion testing can be affected. Daratumumab binds CD38 on red blood cells and can cause a positive indirect antiglobulin test (panagglutination), complicating cross-matching. Blood banks have workarounds, but they need to know you’re on daratumumab; the interference can persist for months after the last dose. Carry documentation and alert clinicians before any planned transfusion. Official DARZALEX HCP WebsitePubMed Central
• HBV reactivation risk. People with current or past hepatitis B need screening and monitoring; treatment may be paused if reactivation occurs. FDA Access Data
• Lab test interference. Because Darzalex is an IgG-kappa antibody, it can show up on serum protein electrophoresis/immunofixation, potentially masking whether a patient has truly reached a complete response. Specialized assays exist if needed. FDA Access Data
• Pregnancy & breastfeeding. Discuss family planning; risks in pregnancy and nursing aren’t fully known, and treatment decisions are individualized. Follow your oncologist’s guidance. FDA Access Data

Drug & Product Interactions

• Metabolic drug–drug interactions are not a focus with monoclonal antibodies like daratumumab (they aren’t processed by liver enzymes the way many pills are).
• The big “interaction” is with blood bank tests and some myeloma response assays (see above). Always share your treatment status with other providers and your blood bank. Official DARZALEX HCP WebsiteFDA Access Data
• Vaccinations: talk with your team about timing; immune responses may be blunted during therapy, and live vaccines are generally avoided in people receiving active myeloma treatment. (Your team will tailor a vaccination plan.) PubMed Central

Darzalex vs. Other Treatments (and Where It Fits)

Multiple myeloma care usually mixes drug “classes” (proteasome inhibitors, IMiDs, steroids, anti-CD38 antibodies, and more). Darzalex has become a cornerstone because it can be layered into many combinations across lines of therapy. The subcutaneous option often improves convenience (minutes vs hours) and has fewer administration-related reactions than IV in many settings, with similar efficacy—your team will choose based on your regimen, access, and preferences. FDA Access Data

Cost & OTC Status

Darzalex is prescription-only specialty medicine and can be expensive. Coverage varies by country and insurer. Manufacturer assistance is available:

• Janssen CarePath / J&J withMe: programs that help eligible patients understand coverage, copays, and possible patient-assistance options. Ask your clinic’s financial counselor or visit the program pages to see what you may qualify for. janssencarepath.com

Special Section: Darzalex IV vs. Darzalex Faspro (SC)

Bottom line: both are effective anti-CD38 therapies; SC is faster and often preferred for convenience, while IV remains appropriate in settings where infusions are standard or SC isn’t suitable. Your team will recommend one based on the full plan. FDA Access Data+1

Proper Care While on Darzalex

• Keep every dose on schedule. The early, more frequent doses are key to getting the medicine “on board.”
• Take premeds exactly as instructed and complete any post-dose steroids to reduce delayed reactions. FDA Access Data
• Use antiviral prophylaxis if prescribed and don’t stop early; it helps prevent shingles. FDA Access Data
• Tell every provider (dentist, ER, surgeons) that you are on daratumumab, and carry a transfusion alert for the blood bank. Official DARZALEX HCP Website
• Call promptly for fevers, chills, cough, severe rash, unusual bruising/bleeding, or shingles-like pain/blisters.
• Ask about vaccines and infection-prevention steps tailored to you. PubMed Central

Frequently Asked Questions (FAQs)

Q1. Is Darzalex chemotherapy?
No. It’s a monoclonal antibody (targeted immunotherapy) that seeks out CD38 on myeloma cells. FDA Access Data

Q2. What’s the difference between Darzalex and Darzalex Faspro?
Same active antibody; Faspro adds hyaluronidase so it can be given as a quick subcutaneous injection at a fixed dose. FDA Access Data

Q3. How long does each treatment take?
First IV infusions can take hours and then shorten; SC injections are usually minutes. Your visit time also includes premeds and monitoring. FDA Access Data

Q4. Why do I need premedications and antiviral pills?
They cut down the risk of administration reactions and shingles reactivation. Don’t skip them unless your team says so. FDA Access Data

Q5. Can Darzalex affect blood transfusions?
Yes. It can make compatibility tests appear “positive.” Tell the blood bank you’re on daratumumab; they have specific methods to get safe, compatible blood. The effect can persist for months after stopping. Official DARZALEX HCP Website

Q6. Does Darzalex interact with my other medicines?
Classic pill-to-pill interactions are not usually the issue; the bigger concern is test interference and overlapping side effects from combination drugs. Share your full med list at every visit. FDA Access Data

Q7. Will it make my lab results confusing?
Sometimes. Because Darzalex is an IgG-kappa antibody, it can appear on certain myeloma protein tests; specialized methods can clarify true response. FDA Access Data

Q8. How soon might I feel better?
Response timing varies widely. Many regimens need several cycles before scans and labs clearly improve. Your team will track markers and symptoms.

Q9. Can I work or travel during treatment?
Often yes, with planning. Ask about infection precautions, clinic schedules, and what to do if you’re far from your treatment center.

Q10. Is Darzalex available over the counter?
No. It’s a prescription-only therapy given under medical supervision. FDA Access Data

Q11. How much does it cost?
Costs vary by location and insurance. Manufacturer support programs and foundations may help with copays or coverage gaps—ask your clinic to connect you. janssencarepath.com

Q12. What happens if I miss a dose?
Contact your clinic. Doses are usually given as soon as possible and the schedule adjusted to maintain the intended interval. Don’t “double up” on your own. FDA Access Data

Final Thoughts

Darzalex has transformed myeloma care and, in its SC formulation, expanded options for people with AL amyloidosis. Whether delivered by infusion or a quick injection, it’s a powerful anti-CD38 therapy that’s most effective when you:

• follow the premedication and dosing schedule closely,
• report side effects early,
• keep antiviral prophylaxis and other supportive meds on track,
• and alert blood banks and other providers that you’re receiving daratumumab. FDA Access DataOfficial DARZALEX HCP Website

With thoughtful monitoring and a team you trust, Darzalex can be used safely and effectively as part of a modern, personalized treatment plan—giving you the best chance to control disease while maintaining quality of life.