Palivizumab Injection
Palivizumab Injection (Synagis) is a monoclonal antibody given by muscle injection to help prevent serious lung infections caused by RSV in certain high-risk babies and young children.
Built from the FDA-approved label, dated Jan 21, 2026 · How this page is built
⚡ Quick answers about Palivizumab Injection
What is Synagis for?
It helps prevent serious RSV lung infections in certain high-risk children. These include babies born early, children with bronchopulmonary dysplasia, and children with significant congenital heart disease.
Read the full answer →How often will my child get it?
It is a shot into the thigh muscle given once a month during RSV season. The first dose comes before the season starts. Keep the monthly schedule even if your child catches RSV.
See it in the FAQ →What side effects should I expect?
The most common ones are fever and rash. Injection site reactions can also happen. These are usually the things to mention at the next visit.
See it in the FAQ →What should make me get help right away?
Severe allergic reactions are rare but serious. Get emergency help for hives, swelling, trouble breathing, bluish skin, limpness, or unresponsiveness. Also tell the doctor about unusual bruising or bleeding.
See it in the FAQ →🧬 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 →
How we combine label and product data →📖 Palivizumab Injection: Patient Information Guide
A plain-language walkthrough of Palivizumab Injection — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
What Palivizumab Injection is used for
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Synagis (palivizumab) is used to prevent serious RSV lung disease in these children:
- Babies born at 35 weeks or earlier who are 6 months old or younger at the start of RSV season.
- Children 24 months or younger at the start of RSV season with bronchopulmonary dysplasia (BPD, a chronic lung condition in infants) that needed medical treatment in the previous 6 months.
- Children 24 months or younger at the start of RSV season with hemodynamically significant congenital heart disease (a heart defect present from birth that affects blood flow).
It is not for treating RSV disease.
How Palivizumab Injection works
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Palivizumab is a humanized monoclonal antibody, a lab-made protein that acts like the body's own antibodies. It gives passive immunity, meaning protection is supplied from outside rather than built by the child's own immune system.
It binds the RSV F protein on the virus surface and blocks a key step the virus needs to fuse with and enter cells. It also stops infected cells from fusing with neighboring cells.
How Palivizumab Injection is taken (dosage)
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Synagis is given as a monthly injection into a muscle, usually the thigh. The first dose comes before RSV season. Remaining doses follow monthly through the season. In the northern hemisphere, the season typically runs about November through April, but it can start earlier or last longer.
- Dosing is based on the child's weight.
- Children who catch RSV should still keep getting monthly doses through the season.
- Children who have heart bypass surgery should get an extra dose as soon as possible afterward, even if less than a month since the last dose.
- Less frequent dosing has not been shown to work.
A healthcare professional prepares and gives each dose. Follow your prescriber's schedule and talk to them if a dose is missed.
Dosing details from the FDA-approved label
From the Palivizumab 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.
- Prevention of RSV disease (recommended dose)
- 15 mg per kg of body weight given monthly by intramuscular injection
- First dose prior to commencement of the RSV season and remaining doses monthly throughout the RSV season
- Children who develop an RSV infection should continue monthly doses throughout the RSV season; injection volumes over 1 mL should be given as a divided dose
- Children undergoing cardio-pulmonary bypass
- An additional dose of Synagis as soon as possible after the cardio-pulmonary bypass procedure (even if sooner than a month from the previous dose)
- Thereafter, doses monthly as scheduled
- Synagis serum levels are decreased after cardio-pulmonary bypass
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION 15 mg per kg of body weight, administered intramuscularly prior to commencement of the RSV season and remaining doses administered monthly throughout the RSV season. ( 2.1 ) Children undergoing cardio-pulmonary bypass should receive an additional dose of Synagis as soon as possible after the cardio-pulmonary bypass procedure (even if sooner than a month from the previous dose). Thereafter, doses should be administered monthly as scheduled. ( 2.1 , 12.3 ) 2.1 Dosing Information The recommended dose of Synagis is 15 mg per kg of body weight given monthly by intramuscular injection. The first dose of Synagis should be administered prior to commencement of the RSV season and the remaining doses should be administered monthly throughout the RSV season. Children who develop an RSV infection should continue to receive monthly doses throughout the RSV season. In the northern hemisphere, the RSV season typically commences in November and lasts through April, but it may begin earlier or persist later in certain communities. Synagis serum levels are decreased after cardio-pulmonary bypass [see Clinical Pharmacology ( 12.3 ) ]. Children undergoing cardio-pulmonary bypass should receive an additional dose of Synagis as soon as possible after the cardio-pulmonary bypass procedure (even if sooner than a month from the previous dose). Thereafter, doses should be administered monthly as scheduled. The efficacy of Synagis at doses less than 15 mg per kg, or of dosing less frequently than monthly throughout the RSV season, has not been established. 2.2 Administration Instructions DO NOT DILUTE THE PRODUCT. DO NOT SHAKE OR VIGOROUSLY AGITATE THE VIAL. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration. Do not use any vials exhibiting particulate matter or discoloration. Using aseptic techniques, attach a sterile needle to a sterile syringe. Remove the flip top from the Synagis vial and wipe the rubber stopper with a disinfectant (e.g., 70% isopropyl alcohol). Insert the needle into the vial and withdraw into the syringe an appropriate volume of solution. Administer immediately after drawing the dose into the syringe. Synagis should be administered in a dose of 15 mg per kg intramuscularly using aseptic technique, preferably in the anterolateral aspect of the thigh.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Palivizumab Injection side effects in detail
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Common side effects
- Fever
- Rash
- Injection site reactions
When to get medical help
- Get emergency help right away for signs of a severe allergic reaction: hives, itching, swelling, trouble breathing, bluish skin color, limpness, very low blood pressure, or unresponsiveness.
- Tell your child's doctor if you notice unusual bruising or bleeding. Severe low platelets (thrombocytopenia) has been reported after approval.
- Call your child's doctor about any worrying reaction after an injection.
In clinical trials, the most common side effects were:
- Fever
- Rash
Injection site reactions have also been reported after approval. The most serious reactions are severe allergic reactions such as anaphylaxis. Severe low platelets (thrombocytopenia) has also been reported. Get emergency help for trouble breathing, swelling, hives, bluish color, limpness, or unresponsiveness.
Palivizumab Injection warnings and precautions
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- Severe allergic reactions: anaphylaxis, including fatal cases, can occur on first use or later. Stop Synagis permanently after a significant reaction.
- Bleeding problems: use caution in children with low platelets or clotting disorders because of the muscle injection.
- Test interference: Synagis may cause false-negative results on some RSV tests, though not on RT-PCR tests.
- Not a treatment: it has not been shown to treat RSV disease.
Palivizumab Injection interactions: what it interacts with
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No formal drug interaction studies were done, but trial experience was reassuring.
- Routine childhood vaccines and flu vaccine: no added side effects seen in a trial.
- Bronchodilators and corticosteroids: no added side effects seen in a trial.
- RSV diagnostic tests: Synagis may cause false-negative results on some tests.
Interactions listed in the FDA-approved label
From the Palivizumab Injection prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Drug-drug interactions (formal studies): No formal drug-drug interaction studies were conducted.
- Routine childhood vaccines, influenza vaccine, bronchodilators, or corticosteroids: In Trial 1 the proportions of children receiving these were similar in the placebo and Synagis groups, and no incremental increase in adverse reactions was observed among children receiving these agents.
Read the label’s full interactions text
7 DRUG INTERACTIONS No formal drug-drug interaction studies were conducted. In Trial 1, the proportions of children in the placebo and Synagis groups who received routine childhood vaccines, influenza vaccine, bronchodilators, or corticosteroids were similar and no incremental increase in adverse reactions was observed among children receiving these agents.
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 Palivizumab Injection
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- Do not use if your child had a previous significant allergic reaction to Synagis.
- Tell the doctor if your child has low platelets or a bleeding or clotting disorder.
- Safety and effectiveness are not established in children older than 24 months at the start of dosing.
- It is not indicated for females of reproductive potential, including pregnancy and breastfeeding.
- Tell the doctor if your child is having heart bypass surgery.
Palivizumab Injection overdose: if you take too much
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Overdoses up to 85 mg per kg have been reported, and some cases had side effects. If too much is given, the child should be watched for signs of side effects and treated for any symptoms.
Pharmacodynamics: what Palivizumab Injection does in the body
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Palivizumab binds the RSV F protein, blocking virus-to-cell fusion and cell-to-cell spread. In lab studies it was active against both RSV A and RSV B strains. In an animal model, blood levels of 40 mcg per mL or higher reduced RSV replication in the lungs 100-fold.
Pharmacokinetics: how your body processes Palivizumab Injection
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After a muscle injection, about 70% of the drug reaches the bloodstream. Its half-life is roughly 20 to 25 days in young children. Blood levels build up over the first several monthly doses.
Levels drop about 58% after heart bypass surgery, which is why an extra dose is given. Gender, age, body weight, and race did not affect trough levels in one study.
How to store Palivizumab Injection
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Upon receipt and until use, Synagis should be stored between 2°C and 8°C (36°F and 46°F) in its original container. DO NOT freeze.
📄 Written from Palivizumab Injection’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Palivizumab Injection
53 supplements and herbal products have documented interactions with Palivizumab Injection in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Moderate · 52
- Minor · 1
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.
🩺 Palivizumab Injection: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Palivizumab Injection — the kind of thing our pharmacy team would talk through with you at the counter.
What is Synagis for?
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How often will my child get it?
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What side effects should I expect?
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What should make me get help right away?
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Can my child still get routine vaccines?
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Will it affect an RSV test?
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Is Palivizumab Injection available over the counter?
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When was Palivizumab Injection first available?
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💬 Answers drafted from Palivizumab Injection’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 More about Palivizumab Injection on HelloPharmacist
💊 Palivizumab Injection forms and strengths (how it comes)
Palivizumab 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.
Injection
How this form is used
- Synagis is used to prevent serious RSV lower respiratory tract disease in certain high-risk children.
- Synagis has not been established as a treatment for RSV disease.
- Synagis is given by intramuscular injection, preferably in the front-outer thigh.
- Synagis should not be diluted or shaken.
- Synagis comes in a single-dose vial with no preservative. Any unused portion is discarded.
- Synagis is given monthly through RSV season, starting before the season begins.
📊 Palivizumab Injection on the U.S. market: products, makers and brands
How Palivizumab 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 4 Palivizumab Injection product records with the FDA, mostly as injection; the earliest marketing or approval year on record is 1998. Brand names on the directory include Synagis; the rest are generics.
📈 How widely Palivizumab Injection is used (Medicaid data)
A general measure of how commonly Palivizumab 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 Palivizumab 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 Palivizumab Injection prescribed? Of the 1,599 medications we measure, Palivizumab Injection ranks #1,205 by Medicaid prescriptions — more than 25% of them.
Utilization by Palivizumab 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.
1 ML palivizumab 100 MG/ML Injection Most dispensed
Summed across the 1 of 1 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1657341
0.5 ML palivizumab 100 MG/ML Injection
Summed across the 1 of 1 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1657361
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 Palivizumab 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 2 of 2 listed Palivizumab Injection NDCs with Medicaid activity.
🔍 Compare Palivizumab Injection products
A representative set of FDA-listed product records for Palivizumab 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 | ||||
| 50 mg/0.5 mL | Intramuscular | Swedish Orphan Biovitrum AB (publ) × 2 listings | BLA | View NDC → |
| 100 mg/mL | Intramuscular | Swedish Orphan Biovitrum AB (publ) × 2 listings | BLA | View NDC → |
Showing 4 of 4 products — FDA National Drug Code Directory. See every product, package size and price: browse all 4 Palivizumab Injection NDCs →
📈 Palivizumab 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 Palivizumab 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 Palivizumab 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.
🏛️ Palivizumab Injection FDA approval history
How Palivizumab Injection went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Palivizumab 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.
Source: openFDA drug enforcement (recall) reports.
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 194279 1 dose form · 2 strengths
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Dose form (SCDF) Injection RxCUI 1657340In current FDA listingsClinical drug / strength (SCD) 0.5 ML palivizumab 100 MG/MLRxCUI 16573611 ML palivizumab 100 MG/MLRxCUI 1657341
Look up RxCUI 194279 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.
📦 Palivizumab Injection supply and shortage status
Whether Palivizumab 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.
🏷️ Palivizumab Injection brand names
Palivizumab Injection is sold under one brand name in the FDA directory — Synagis. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
🏭 Who makes Palivizumab Injection: manufacturers and labelers
One company lists Palivizumab Injection products with the FDA. By number of product records, the largest are Swedish Orphan Biovitrum AB (publ). Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Palivizumab Injection drug class (RxNorm)
Palivizumab Injection belongs to the Respiratory Syncytial Virus Anti-F Protein Monoclonal Antibody 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 Palivizumab 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 we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Swedish Orphan Biovitrum AB (publ) is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.