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Immunization Reactions

Reactions to vaccines are common and almost always harmless. Severe allergic (anaphylactic) reactions to any vaccine are possible, but they are extremely rare or have never been reported. Listed below are the symptoms for a severe allergic reaction as well as common reactions to specific vaccines.

What should I do if my child has a severe allergic reaction?

CALL 911 IMMEDIATELY if you notice the following severe allergic reactions:

  • trouble breathing
  • weakness
  • wheezing
  • fast heartbeat
  • hives
  • dizziness
  • paleness
  • swelling of the throat.

What are the possible reactions to the different vaccines?

The percentage listed next to each reaction shows the percentage of children who have this reaction.

Diphtheria-Tetanus-Pertussis (DTaP)

  • Pain, tenderness, swelling, or redness at the injection site for 24 to 48 hours (25% to 45%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Fever for 24 to 48 hours (15% to 25%). Give your child ibuprofen or acetaminophen if the fever is over 102F (38.9C). The next time your child gets a DTaP shot, give your child acetaminophen at your health care provider's office and continue the medicine every 4 to 6 hours for 24 hours.
  • Mild drowsiness (15%), poor appetite (10% to 15%) for 24 to 48 hours, or prolonged crying (>3 hours) (4%).
  • Painless lump at the injection site 1 or 2 weeks later. The lump is harmless and will disappear in about 2 months. Call your provider within 24 hours if it turns red or is tender.

CALL YOUR PROVIDER IMMEDIATELY IF the following rare but serious reactions occur:

  • Fever over 104F, or 40.0C (0.4%)
  • Crying for more than 3 hours (1%)
  • High-pitched, unusual cry (0.1%)
  • Convulsions (very rare)
  • Collapse with shocklike state (very rare)
  • Any other unusual reaction.

Measles, Mumps, Rubella (MMR)

These reactions may begin 7 to 10 days after getting the vaccine:

  • Fever of 101F to 103F (38.3C to 39.5C) for 2 or 3 days (10%). Give your child ibuprofen or acetaminophen if the fever is over 102F (38.9C). Call your provider within 24 hours if the fever lasts over 72 hours or is over 104F (40C).
  • A mild pink rash mainly on the body (5%). No treatment is necessary. The rash will last 2 to 3 days. Call your provider immediately if the rash changes to purple spots. Call within 24 hours if the rash becomes itchy or the rash lasts more than 3 days.

Polio Vaccine (IPV)

  • Sore injection site (rare). No treatment is necessary. Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Fever (1% to 4%). Give your child ibuprofen or acetaminophen if the fever is over 102F (38.9C).

Pneumococcal Vaccine (PCV7)

  • Fever, usually, mild (10%). Give your child ibuprofen or acetaminophen if the fever is over 102F (38.9C).
  • Redness, tenderness, or swelling at the shot site (30%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.

Hemophilus Influenza Type B Vaccine (HIB)

  • Sore injection site (up to 25%) or mild fever (5%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.

Hepatitis B Vaccine (Hep B)

  • Sore injection site (10% to 25%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Fever (up to 7%). Give your child ibuprofen or acetaminophen if the fever is over 102F (38.9C).

Chickenpox Vaccine (VAR)

  • Never give your child aspirin for any symptom within 6 weeks of receiving the vaccine. (Reye's syndrome has been linked with the use of aspirin to treat fever or pain caused by a virus.) For fever or pain, give ibuprofen or acetaminophen.
  • The chickenpox vaccine may cause pain or swelling at the injection site for 1 to 2 days (20%).
  • Some children (15%) may have a fever that begins 2 to 4 weeks after the vaccination and lasts 1 to 3 days. Give your child ibuprofen or acetaminophen if the fever is over 102F (38.9C).
  • A few children (3%) develop a mild rash at the injection site or elsewhere on the body. The rash begins 5 to 26 days after the vaccine, looks like a few (2 to 10) chickenpox sores, and usually lasts a few days.

Children with these rashes can go to day care or school. If the vaccine rash contains fluid, cover it with clothing or a Band-Aid. Avoid school if there are widespread, weepy sores (because this may be real chickenpox).

Hepatitis A Virus (HAV) Vaccine

  • Sore injection shot site (20% to 50%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Headache or fatigue (less than 10%).

Influenza Virus Vaccine

  • Pain, tenderness, or swelling at the injection site within 6 to 8 hours (10%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Fever of 101F to 103F, or 38.3C to 39.5C (18%). Fevers mainly occur in young children. Give your child acetaminophen or ibuprofen for fever over 102F (38.9C).

Meningococcal Conjugate Vaccine

  • Pain, soreness at the vaccination site (60%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Fatigue (30%)
  • Painful joints (15-20%)
  • Decrease in appetite (10%)
  • Guillain-Barr syndrome is a very rare but serious side effect.

Tdap vaccine

  • Pain, soreness at the vaccination site (60%). Giving your child ibuprofen or acetaminophen and placing a cold, wet washcloth over the tender area may provide some relief.
  • Low-grade fever (10%). Give your child acetaminophen or ibuprofen for fever over 102F (38.9C).
  • Headache (40%)
  • Fatigue (30%)
Written by B.D. Schmitt, MD and Robert Brayden, MD.
Published by McKesson Provider Technologies.
Last modified: 2006-05-23
Last reviewed: 2006-02-06
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
Copyright 2006 McKesson Corporation and/or one of its subsidiaries. All Rights Reserved.
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