Springdale Mason Pediatrics

Vaccine Reactions - Normal

Definition

  • A reaction to a recent immunization (vaccine) shot
  • Most reactions are at the injection site (such as pain, swelling, redness)
  • General reactions (such as a fever or being fussy) also are common

Call or Return If

  • Redness starts after 2 days (48 hours)
  • Redness becomes larger than 2 inches (5 cm)
  • Pain or redness gets worse after 3 days
  • Pain or redness lasts more than 7 days
  • Fever starts after 2 days
  • Fever lasts more than 3 days
  • You think your child needs to be seen
  • Your child becomes worse

About This Topic

Symptoms

  • Shot sites can have swelling, redness and pain. Most often, these symptoms start within 24 hours of the shot. They most often last 3 to 5 days. With the DTaP vaccine, they can last up to 7 days. This is a normal reaction to the vaccine, not an infection. It is usually the only side effect of the vaccine.
  • In some children, severe swelling can occur with the 4th (15 months) DTaP shot. The swelling can be up to 2 inches (5 cm). Swelling up to 3 inches (7.5 cm) can normally occur with 5th (4 years) dose. This is not an allergic reaction. Future DTaP vaccines are safe to give.
  • Any hives and itching around the shot site is normal. It does not mean your child is allergic to the vaccine.
  • Fever with most vaccines begins within 24 hours and lasts 1 to 2 days.
  • With the MMR and chickenpox shots, fever and rash occurs in 10% of children. These symptoms start later. They usually begin between 1 and 4 weeks.
  • Severe allergic reactions are very rare, but can occur with any vaccine. They start within 2 hours.
  • Abnormal reaction: A secondary bacterial infection at the shot site. This is very rare (less than 1 per 1000). Suspect if the redness or fever begins over 48 hours after the shot was given. Also, be on the lookout for redness or pain that increases after 3 days.

Causes

  • The vaccines contain substances that turn on your immune system.
  • About 25% of children have a skin reaction to the substances at the shot site.
  • This happens most with the DTaP vaccine. However, it can happen with other vaccines, including the flu vaccine.
  • It means the vaccine is doing what it is supposed to do.

After Care Advice

Overview:
  • Immunizations (vaccines) protect your child against serious diseases.
  • All of these reactions mean the vaccine is working.
  • Your child's body is making new antibodies to protect against the real disease.
  • There is no need to see your child's doctor for normal reactions. Examples of normal reactions are redness around the shot site and fever. Redness and fever starting on day 1 of the shot is always normal.
  • Here is some care advice that should help.
Reaction at Shot Site:
  • Cold Pack: For pain at the shot site, use a cold pack. You can also put ice in a wet washcloth on the sore shot site. Use for 20 minutes as needed.
  • Pain Medicine: To help with the pain, give acetaminophen (such as Tylenol) or ibuprofen. Use as needed.
  • Hives at the Shot Site: If itchy, can put on 1% hydrocortisone cream. No prescription is needed. Use twice daily as needed.
Fever:
  • Fever with most vaccines begins within 12 hours and lasts 2 to 3 days. This is normal, harmless and possibly helpful. Fevers may improve antibody production.
  • For fevers above 102° F (39° C), give acetaminophen (such as Tylenol). If over 6 months old, can give ibuprofen.
  • For all fevers: Give extra fluids. Keep your child well hydrated.
General Reactions:
  • All vaccines can cause mild fussiness, crying and restless sleep. This is usually because of a sore shot site.
  • Some children sleep more than usual. A decreased appetite and activity level are also common.
  • These symptoms are normal. They do not need any treatment.
What to Expect:
  • Most local reactions last 2 or 3 days.
  • Most fever lasts 2 days.

Author: Barton Schmitt MD, FAAP
Copyright 2000-2020 Schmitt Pediatric Guidelines LLC
Disclaimer: This health information is for educational purposes only. You the reader assume full responsibility for how you choose to use it.
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