Side effects of MMR and varicella vaccine

These vaccines use weakened forms or components that help the immune system recognise measles, mumps, rubella or chickenpox. Local soreness, redness and swelling are common responses to an injection. A mild fever or rash may appear after a delay as immunity develops. Some people notice temporary tiredness or swollen glands. A small chickenpox-like rash can occur after varicella vaccination and should be covered if it appears. These effects do not mean the person has ordinary chickenpox, but an unwell child or adult needs assessment.

Offer fluids, rest and comfortable clothing. Keep the injection area clean and avoid scratching. Follow the clinician’s advice about fever or pain relief, using an age-appropriate product where advised. If a blister-like rash appears, avoid close contact with people who are pregnant or have significant immune suppression until a clinician gives guidance. Keep the vaccination record and note the vaccine date and any reaction.

Seek emergency care for breathing difficulty, facial or throat swelling, collapse, or widespread hives. Contact a clinician promptly for a persistent high fever, severe headache, confusion, a seizure, dehydration, or a rapidly spreading blistering rash. A medical review is also sensible if symptoms are getting worse instead of settling, or if the person has an immune condition or is taking immune-suppressing medicine.

Ask which vaccine was given, when reactions might appear, how to manage fever, whether contact precautions are needed for a rash, and whether allergies, pregnancy or immune treatment affect future doses.