Rezafungin Injection
Rezafungin is an antifungal medicine used to treat candidemia (a Candida bloodstream infection) and invasive candidiasis (a serious Candida infection spreading through the body) in adults and certain adolescents.
🧬 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 →
Rezafungin (Rezzayo) is a newer echinocandin antifungal, on the U.S. market since about 2023, that kills Candida yeast in the bloodstream or deeper tissues by blocking an enzyme the yeast needs to build its cell wall; it is reserved for patients 12 and older with limited other options. It is generally well tolerated, and nausea, diarrhea and low potassium are the side effects reported most. Watch above all for a serious allergic reaction, and tell the nurse right away about hives, chest tightness or trouble breathing during or after the infusion. Infusions into a vein run once a week in a clinic or hospital, for up to four doses, with regular liver tests.
Clinical pearls
- Tell the care team about any past reaction to caspofungin, micafungin or anidulafungin, because those allergies rule out rezafungin.
- Protect your skin from sun and tanning beds during treatment, because rezafungin can make skin more sensitive to UV light.
- Expect blood draws for potassium, magnesium and liver tests, since low levels and liver changes are both reported with rezafungin.
- Because each dose covers a full week, keep every infusion appointment, since a missed visit leaves a longer gap than daily antifungals would.
Patient information guide A plain-language walkthrough of Rezafungin Injection, written from its FDA label.
What Rezafungin Injection is used for
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Rezafungin injection (brand name Rezzayo) is an antifungal used for serious Candida infections in adults and adolescents 12 years of age and older who have limited or no other treatment options.
- Candidemia: Rezzayo treats Candida yeast infections in the bloodstream.
- Invasive candidiasis: Rezzayo treats serious Candida infections that have spread into the body's organs or tissues.
- Rezzayo has not been studied for Candida infections of the heart (endocarditis), bones (osteomyelitis), or brain and spinal cord lining (meningitis) — it is not used for those forms.
- Approval of Rezzayo is based on a limited amount of clinical safety and efficacy data.
How Rezafungin Injection works
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Rezafungin is an echinocandin antifungal — a class of drugs that attacks fungi in a way that does not harm human cells. It works by blocking a key enzyme called 1,3-β-D-glucan synthase, which Candida fungi rely on to build their outer cell wall. Without a stable cell wall, the fungal cells fall apart and the infection cannot spread.
Because human cells do not use this enzyme at all, echinocandins like rezafungin can target the fungus precisely. Rezafungin also does not interfere with the liver's drug-processing enzymes (the CYP450 system), which means it is unlikely to cause problems by changing how other medications work in your body.
Rezafungin Injection dosage
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Rezzayo is given by intravenous (IV) infusion — a slow drip into a vein over about one hour — once a week in a healthcare setting. The first dose is a larger loading dose; after that, a smaller maintenance dose is given once weekly. Treatment is generally limited to up to 4 weekly doses total.
- If a scheduled dose is missed, it should be given as soon as possible; your care team will adjust the schedule based on how late the dose was.
- If dosing is interrupted for 2 weeks or more, treatment is restarted with the larger loading dose.
Dosing details from the FDA-approved label
From the Rezafungin 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.
- Adults and pediatric patients 12 years of age or older
- Once weekly by intravenous (IV) infusion, with an initial 400 mg loading dose, followed by a 200 mg dose once weekly thereafter
- Administer by intravenous infusion over approximately one hour (~250 mL/h)
- The safety of REZZAYO has not been established beyond 4 weekly doses
- Missed doses
- Administer the missed dose as soon as possible
- If administered within 3 days of the assigned day, the next weekly dose may be given on schedule
- If administered more than 3 days after the assigned day, revise the dosing schedule to ensure there are at least 4 days before the next dose
- If restarting after at least 2 weeks of missed dosing, start again at th
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Administer the recommended dosage of REZZAYO once weekly by intravenous (IV) infusion, with an initial 400 mg loading dose, followed by a 200 mg dose once weekly thereafter. The safety of REZZAYO has not been established beyond 4 weekly doses. ( 2.1 ) See full prescribing information for reconstitution, dilution, and administration instructions. ( 2.2 , 2.3 , 2.4 ) 2.1 Recommended Dosage for Adults and Pediatric Patients 12 Years of Age or Older Administer the recommended dosage of REZZAYO once weekly by intravenous (IV) infusion, with an initial 400 mg loading dose, followed by a 200 mg dose once weekly thereafter. The safety of REZZAYO has not been established beyond 4 weekly doses [see Adverse Reactions ( 6.1 )] . REZZAYO is for intravenous infusion only [see Dosage and Administration ( 2.4 )] . 2.2 Missed Doses If a scheduled dose is missed (not taken on the assigned day), administer the missed dose as soon as possible. If the missed dose is administered within 3 days of the assigned day, the next weekly dose may be given on schedule. If the missed dose is administered more than 3 days after the assigned day, revise the dosing schedule to ensure there are at least 4 days before the next dose. If restarting after at least 2 weeks of missed dosing, the dosing should be started again at the 400 mg loading dose. 2.3 Preparation and Administration of REZZAYO Reconstitution REZZAYO is supplied as a single-dose vial containing 200 mg of rezafungin. For the 400 mg dose, aseptically reconstitute two vials each with 9.5 mL of sterile Water for Injection, to provide a concentration of 20 mg/mL in each vial. For the 200 mg dose, aseptically reconstitute one vial with 9.5 mL of sterile Water for Injection, to provide a concentration of 20 mg/mL. Swirl gently to dissolve the white to pale yellow cake or powder. Avoid shaking to minimize foaming. The solution should be clear to pale yellow after dissolution. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Do not use if the reconstituted solution is cloudy or has precipitated. The reconstituted solution is not for direct injection and must be diluted before intravenous infusion.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Rezafungin Injection side effects
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The most common side effects reported with Rezzayo (occurring in 5% or more of patients in clinical trials) include:
Common side effects
- Low potassium levels (hypokalemia)
- Fever (pyrexia)
- Diarrhea
- Anemia (low red blood cell count)
- Vomiting
- Nausea
- Low magnesium levels (hypomagnesemia)
- Abdominal pain
- Constipation
- Low phosphate levels (hypophosphatemia)
When to get medical help
- Call for emergency help right away if you have signs of a severe allergic reaction (anaphylaxis): hives, difficulty breathing, swelling of the face or throat, or a rapid drop in blood pressure
- Tell your nurse immediately if you feel flushing, warmth, chest tightness, or nausea during the infusion — these can be infusion-related reactions
- Tell your doctor if your skin becomes very sensitive to sunlight or you develop a rash after UV exposure
- Report any signs of liver problems: yellowing of the skin or eyes, dark urine, severe stomach pain, or unusual fatigue
More serious reactions — including severe allergic reactions (anaphylaxis), infusion-related reactions, liver test abnormalities, and skin sensitivity to sunlight — require prompt medical attention; see the warnings section for details.
Rezafungin Injection warnings and precautions
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- Severe allergic reactions (anaphylaxis): Life-threatening allergic reactions have been reported with Rezzayo. If you experience hives, difficulty breathing, swelling, or a sudden drop in blood pressure during or after the infusion, emergency treatment is needed immediately.
- Infusion-related reactions: Flushing, a feeling of warmth, hives, nausea, or chest tightness can occur during the IV drip. Tell your nurse right away — slowing or pausing the infusion usually helps.
- Liver effects: Abnormal liver test results have been seen in patients taking Rezzayo, particularly those with serious underlying conditions taking multiple medications. Your care team will monitor your liver function during treatment.
- Photosensitivity (sun sensitivity): Rezzayo may make your skin more sensitive to sunlight and UV light. Use sunscreen, protective clothing, and avoid prolonged sun exposure while being treated.
Rezafungin Injection interactions
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Based on clinical studies, rezafungin is not expected to significantly affect the blood levels of most common medications, including cyclosporine, tacrolimus, metformin, digoxin, and several others. It does not inhibit or induce the liver enzymes (CYP450) that process many drugs.
- Cyclosporine and tacrolimus (immune-suppressing drugs): No clinically significant interaction expected — but these are complex medications; your team will still monitor levels.
- Metformin (diabetes drug): No clinically significant interaction expected.
- Digoxin (heart medication): No clinically significant interaction expected.
- Other echinocandin antifungals: If you've had an allergic reaction to any echinocandin, Rezzayo is contraindicated — this is a safety concern, not a drug interaction per se.
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.
Before taking Rezafungin Injection
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- Allergy to echinocandins: Rezzayo must not be used if you have a known allergy to rezafungin or any other echinocandin antifungal (such as caspofungin, micafungin, or anidulafungin).
- Pregnancy: There are no human studies on Rezzayo use during pregnancy. Animal studies showed no harm to developing offspring, but this does not guarantee safety in humans. Discuss the risks and benefits with your doctor.
- Breastfeeding: Rezafungin was found in rat milk, so it may pass into human breast milk. Talk to your doctor about the risks to a nursing infant versus your need for treatment.
- Males planning to father children: Animal studies showed potential effects on sperm. The impact on human fertility is unknown — discuss this with your doctor.
- Children under 12: Rezzayo's safety and effectiveness have not been established in patients younger than 12 years old.
- Older adults (65+): Rezzayo has been used in patients up to age 91; no dose adjustment is needed, but data in this age group are limited.
- Liver problems: Rezzayo can affect liver function. Your doctor will monitor liver tests during treatment; tell them if you have pre-existing liver disease.
- Kidney problems or dialysis: Kidney function does not meaningfully affect how the body handles rezafungin, and dialysis is not expected to remove it from the body.
Rezafungin Injection overdose
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No overdose cases were reported during clinical studies of Rezzayo. Because rezafungin binds very tightly to proteins in the blood, it is not expected to be removed by dialysis. If an overdose is suspected, contact your healthcare team or a poison control center immediately.
What Rezafungin Injection does in the body
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At the recommended dosing schedule, rezafungin reaches drug levels in the body that sit on the plateau of its efficacy curve — meaning the doses used are sufficient to achieve the full antifungal effect. Rezafungin does not meaningfully affect heart rhythm (specifically, it does not prolong the QTc interval, a measure of electrical activity in the heart) even at doses well above the approved level.
How your body processes Rezafungin Injection
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Rezafungin is given directly into the bloodstream by IV infusion, so it reaches peak levels in the blood by the end of the one-hour infusion. It binds heavily to blood proteins (roughly 88–99% bound) and distributes into body tissues. The drug has a long half-life of about 152 hours (roughly 6 days), which is why once-weekly dosing works well.
Rezafungin is not broken down by the liver's main enzyme system (CYP450), and it is primarily eliminated through the feces (about 74%) rather than the urine. Kidney disease, liver disease, age, weight, and sex do not meaningfully change how the body handles the drug, so no dose adjustments are needed for those factors. Adolescents 12 and older are expected to have somewhat higher drug exposures than adults on the same dose, but these levels remain within the range seen safely in adults.
How to store Rezafungin Injection
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stored at 20°C to 25°C (68°F to 77°F). stored between 5°C (41°F) and 25°C (77°F) for up to 24 hours . stored between 5°C (41°F) and 25°C (77°F) for up to 48 hours.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Rezafungin Injection
38 supplements and herbal products have documented interactions with Rezafungin Injection in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 3
- Moderate · 35
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.
Rezafungin Injection: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Rezafungin Injection — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is Rezzayo used for?
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How is this medication given — do I take a pill at home?
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What side effects should I watch out for?
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Will this medication interact with my other drugs?
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Is it safe to go outside in the sun while I'm getting this treatment?
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I'm pregnant — is Rezzayo safe to use?
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Is Rezafungin Injection available over the counter?
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When was Rezafungin Injection first available?
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Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Rezafungin Injection on HelloPharmacist
Rezafungin Injection forms and strengths (how it comes)
Rezafungin 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 Rezafungin Injection inactive ingredients by manufacturer.
Injection
How this form is used
- Rezzayo is used to treat candidemia (Candida bloodstream infection) in adults and adolescents 12 years and older with limited or no alternative treatment options
- Rezzayo is used to treat invasive candidiasis (serious Candida infection spreading through body tissues) in adults and adolescents 12 years and older with limited or no alternative treatment options
- Rezzayo is given by intravenous (IV) infusion only — it cannot be given by any other route
- Rezzayo is infused over approximately one hour, once weekly; the first dose is a larger loading dose followed by smaller weekly doses
- Rezzayo must be reconstituted and diluted by a healthcare professional before administration; do not use if the solution is cloudy or has particles
- If you experience flushing, chest tightness, or nausea during the Rezzayo infusion, tell your nurse immediately — the infusion rate can be slowed or paused
Rezafungin Injection on the U.S. market: products, makers and brands
How Rezafungin 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.
1 company lists 1 Rezafungin Injection product record with the FDA, mostly as injection; the earliest marketing or approval year on record is 2023. Brand names on the directory include Rezzayo; the rest are generics.
How widely Rezafungin Injection is used (Medicaid data)
A general measure of how commonly Rezafungin Injection is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Rezafungin Injection is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Rezafungin Injection prescribed? Of the 1,601 medications we measure, Rezafungin Injection ranks #1,471 by Medicaid prescriptions — more than 8% of them.
Utilization by Rezafungin Injection product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
rezafungin 200 MG Injection
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 2639160
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Rezafungin Injection, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 2 listed Rezafungin Injection NDCs with Medicaid activity.
Compare Rezafungin Injection products
A representative set of FDA-listed product records for Rezafungin Injection — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 200 mg | Intravenous | Melinta Therapeutics, LLC | NDA | View NDC → |
Showing 1 of 1 products — FDA National Drug Code Directory. See every product, package size and price: browse all 1 Rezafungin Injection NDCs →
Rezafungin Injection side effects reported to the FDA (FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Rezafungin Injection — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Rezafungin Injection in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
Rezafungin Injection FDA approval history
How Rezafungin Injection went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Rezafungin 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 Rezafungin recalls since July 2021.
✅No Rezafungin recalls on record since July 2021Source: 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.
RxCUI 2639155 1 dose form · 1 strength
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Dose form (SCDF) Injection RxCUI 2639159In current FDA listingsClinical drug / strength (SCD) 200 MGRxCUI 2639160
Look up RxCUI 2639155 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.
Rezafungin Injection supply and shortage status
Whether Rezafungin Injection is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
Rezafungin Injection brand names
Rezafungin Injection is sold under one brand name in the FDA directory — Rezzayo. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Rezafungin Injection: manufacturers and labelers
One company lists Rezafungin Injection products with the FDA. By number of product records, the largest are Melinta Therapeutics, LLC. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Rezafungin Injection drug class (RxNorm)
Rezafungin Injection belongs to the Echinocandin Antifungal class.
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 Rezafungin 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.
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. Melinta Therapeutics, LLC 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 →