Licensed vaccine product
Varivax: side effects, ingredients & package insert
Merck Sharp & Dohme LLC · varicella (chickenpox) vaccine · live attenuated · intramuscular_or_subcutaneous · 0.5 mL
Varivax ingredients (FDA package insert, Section 11)
Per-dose composition as stated in the prescribing information; verified 2026-07-09. Click an ingredient for every vaccine that contains it.
| Role | Ingredient | Amount per dose |
|---|---|---|
| Antigen | Varicella-zoster virus (live, attenuated) | ≥1350 PFU per 0.5 mL |
| Preservative | None (preservative-free) | Single-dose presentation; label states no preservative. |
| stabilizer | Sucrose | ≈24 mg |
| stabilizer | Hydrolyzed gelatin | ≈12.0 mg |
| buffer | Sodium chloride | ≈3.1 mg |
| stabilizer | Monosodium L-glutamate | ≈0.5 mg |
| buffer | Sodium phosphate dibasic | ≈0.44 mg |
| buffer | Potassium phosphate monobasic | ≈0.08 mg |
| buffer | Potassium chloride | ≈0.08 mg |
| residual_manufacturing | MRC-5 residual DNA/protein | trace |
| antibiotic_residual | Neomycin | trace |
| residual_manufacturing | Fetal bovine serum | trace |
| residual_manufacturing | EDTA | trace |
Source: DailyMed. Formulations change — re-verify before clinical use.
Varivax side effects: where the data is
Reported reactions for Varivax and the other varicella (chickenpox) products are compiled on the varicella (chickenpox) vaccine page: pre-licensure trial reactogenicity, VAERS report counts, and international databases (Canada Vigilance, EudraVigilance, Lareb, VigiAccess). Those counts are spontaneous reports with no denominator — a report does not establish that the vaccine caused the event.
Varivax lot number lookup
VAERS report counts are available by lot for Varicella / Zoster vaccines. Use the varicella (chickenpox) lot number lookup or search any lot directly in the lot explorer. Lot numbers are printed on the vaccination record card and the vial label.
Schedule and age range
Licensed ages and the recommended series for varicella (chickenpox) vaccines are on the varicella (chickenpox) vaccine page; how 31 countries schedule it is on varicella (chickenpox) schedule by country. Always confirm the product-specific age range in the current package insert.
Common questions about Varivax
What are the side effects of Varivax?
Common reactions listed in the Varivax package insert are injection-site pain, redness or swelling and short-lived systemic symptoms such as fever, tiredness or irritability. Rarer events and the reported counts from VAERS and international databases are on the varicella (chickenpox) vaccine page; counts are reports, not rates, and do not prove the vaccine caused the event.
What is in Varivax?
Varivax contains Varicella-zoster virus (live, attenuated) as antigen; adjuvant: none; it is preservative-free. Excipients: Sucrose, Hydrolyzed gelatin, Sodium chloride, Monosodium L-glutamate, Sodium phosphate dibasic, Potassium phosphate monobasic, Potassium chloride, MRC-5 residual DNA/protein, Neomycin, Fetal bovine serum, EDTA. Amounts per dose are in the table above, taken from Section 11 of the FDA package insert (verified 2026-07-09).
Where is the Varivax package insert?
The FDA-licensed prescribing information for Varivax is published by Merck Sharp & Dohme LLC and the FDA; the source used for this page is https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=524cf052-e90e-4595-af0a-608edbe9bd31. Formulations change, so re-verify the current insert before clinical use.
Reviewed 2026-10-08 · Matthew Thomas J Halma, Founder, Open Source Medicine Foundation. Informational, not medical advice.