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Symptom Checker

Reactions After Immunizations

A vaccine reaction is a symptom that occurs as the immune system responds to a vaccination. Mild soreness, redness, swelling, fussiness or fever can occur after some vaccines.

Most reactions come from the expected immune response or irritation at the injection site. Allergic reactions and other serious vaccine reactions are much less common. Symptoms that happen after vaccination can also be unrelated to the vaccine.

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AAP Guide to Reactions After Immunizations

The AAP guide below explains common vaccine reactions, what you can do at home, and when to contact us.

AAP Symptom CheckerAfter immunizations

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Symptom CheckerAfter immunizations New tab

When to see a doctor

Contact your pediatrician or another healthcare professional if:

  • Fever or other symptoms are severe or last longer than expected.
  • Redness or swelling at the injection site keeps spreading or becomes increasingly painful.
  • Your child cries inconsolably for a prolonged period or seems very ill.
  • You are worried about a reaction after vaccination.

Call 911 or get emergency care if:

  • Your child has trouble breathing.
  • Your child develops swelling of the tongue, throat or face with other allergic symptoms.
  • Your child collapses or has another sign of a severe allergic reaction.

Talk to a nurse now, at any hour

When can my child be seen

Be seen today.

Every office keeps same-day appointments for illness and injury.

This evening or at the weekend.

Most offices run After Hours Care, by appointment rather than walk-in.

If you are worried, call. We would rather answer a question that turns out to be nothing.

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