Immunization Reactions

When To Call

Call 911 Now (your child may need an ambulance) If

• Difficulty with breathing or swallowing
• Not moving or very weak
• Unresponsive or difficult to awaken

Call Your Doctor Now (night or day) If

• Your child looks or acts very sick
• Age under 12 weeks with fever above 100.4° F (38.0° C) rectally (Caution: Do NOT give your baby any fever medicine before being seen.)
• Fever over 104° F (40° C) and not improved 2 hours after fever medicine
• High-pitched, unusual crying present over 1 hour
• Crying continuously for over 3 hours
• Redness or red streaking around the injection site begins over 48 hours (2 days) after the shot
• Redness or red streak around the injection site becomes larger than 1 inch (2.5 cm) (over 2 inches (5 cm) for 4th DTaP and over 3 inches (7.5 cm) for 5th DTaP)
• You think your child needs to be seen urgently

Call Your Doctor Within 24 Hours (between 9 am and 4 pm) If

• You think your child needs to be seen, but not urgently
• Fever present for more than 3 days
• Fever returns after gone for over 24 hours
• Measles vaccine rash (onset day 6 to 12) persists over 4 days

Call Your Doctor During Weekday Office Hours If

• You have other questions or concerns
• Redness, swelling or pain at the injection site persists over 3 days and is getting worse
• Fussiness from vaccine persists over 3 days

Parent Care at Home If

• Normal immunization reaction and you don't think your child needs to be seen

Care Advice

Treatment for Common Immunization Reactions

1. Reassurance:
• Immunizations (vaccines) protect your child against serious diseases.
• All of these reactions mean the vaccine is working.
• Your child's body is producing new antibodies to protect against the real disease.
• Most of these symptoms will only last 2 or 3 days.
• There is no need to see your child's doctor for normal reactions.
2. Local Reaction at Injection Site:
• Cold Pack: For initial pain or tenderness at the injection site with any vaccine, apply a cold pack or ice in a wet washcloth to the area for 20 minutes as needed.
• Pain Medicine: Give acetaminophen (e.g., Tylenol) or ibuprofen. (See Dosage table)
• Localized Hives: If itchy, can apply 1% hydrocortisone cream (no prescription needed) once or twice.
3. Fever:
• Fever with most vaccines begins within 12 hours and lasts 2 to 3 days. This is normal and harmless.
• For fevers above 102° F (39° C), give acetaminophen (If over 6 months old, okay to give ibuprofen) (See Dosage table)
• For all fevers: Give extra fluids. Avoid excessive clothing or blankets (bundling).
4. General Reaction:
• All vaccines can cause mild fussiness, irritability and restless sleep. While this is usually due to a sore injection site, sometimes the cause is less clear.
• Some children sleep more than usual. A decreased appetite and activity level are also common.
• These symptoms do not need any treatment and will usually resolve in 24-48 hours.
5. Call Your Doctor If:
• Redness becomes larger than 1 inch (2.5 cm) (over 2 inches (5 cm) with 4th DTaP or over 3 inches (7.5 cm) with 5th DTaP)
• Pain, swelling or redness gets worse after 3 days (or lasts over 7 days)
• Fever starts after 2 days (or lasts over 3 days)
• Your child becomes worse

Specific Immunization Reactions

1. Chickenpox Vaccine:
• Pain or swelling at the injection site for 1 to 2 days (in 19% of children)
• Mild fever lasting 1 to 3 days begins 17 to 28 days after the vaccine (in 14%). Give acetaminophen or ibuprofen for fever over 102° F (39°C).
• Never give aspirin for fever, pain or within 6 weeks of receiving the vaccine (Reason: risk of Reye's syndrome - a rare but serious brain disease)
• Chickenpox-like vaccine rash (usually 2 lesions) at the injection site (in 3%)
• Chickenpox-like vaccine rash (usually 5 lesions) scattered over the body (in 4%)
• This mild rash begins 5 to 26 days after the vaccine and usually lasts a few days.
• Children with these vaccine rashes can go to child care or school. (Reason: for practical purposes, vaccine rashes are not contagious)
• EXCEPTION: avoid school if widespread, weepy lesions (Reason: probably actual chickenpox).
• Precaution: if vaccine rash contains fluid, cover it with clothing or Band-Aid.
2. DTaP or DT Vaccine: The following harmless reactions to DTaP can occur:
• Pain, tenderness, swelling or redness at the injection site (in 25% of children) and lasts for 2 to 7 days.
• Fever (in 25% of children) and lasts for 24 to 48 hours
• Mild drowsiness (30%), fretfulness (30%) or poor appetite (10%) and lasts for 24 to 48 hours.
• A large swelling over 4 inches (10 cm) arm can follow the 4th or 5th dose of DTaP occurs in 5% of children. Most children can still move the leg or arm normally. The area of redness is smaller.
• The large thigh or upper arm swelling resolves without treatment by day 3 (60%) to day 7 (90%). This is not an allergy and future DTaP vaccines are safe to give.
3. Hemophilus Influenza Type B Vaccine (Hib):
• No serious reactions reported
• Sore injection site or mild fever only occurs in 1.5% of children
4. Hepatitis A Vaccine:
• No serious reactions reported
• Sore injection occurs in 20% of children, loss of appetite in 10%, and headache in 5%.
• Usually no fever.
• If these symptoms occur, they usually last 1-2 days.
5. Hepatitis B Virus Vaccine (HBV):
• No serious reactions reported
• Sore injection site occurs in 30% of children and mild fever in 3% of children
• Because fever from the vaccine is rare, any infant under 2 months with a fever following the Hep B vaccine should be examined.
6. Influenza Virus Vaccine:
• Pain, tenderness or swelling at the injection site occurs within 6 to 8 hours in 10% of children.
• Mild fever under 103° F (39.5° C) occurs in 18% of children.
• Fevers mainly occur in young children.
• Nasal Influenza Vaccine: Congested or runny nose, mild fever.
7. Measles Vaccine:
• The measles vaccine can cause a fever (10% of children) and rash (5% of children) about 6 to 12 days following the injection.
• Mild fever under 103° F (39.5°C) in 10% and lasts 2 or 3 days.
• The mild pink rash is mainly on the trunk and lasts 2 or 3 days.
• No treatment is necessary. Your child is not contagious.
• Call Your Doctor If:
• Rash becomes very itchy
• Rash changes to purple spots
• Rash lasts over 3 days
8. Meningococcal Vaccine:
• No serious reactions
• Sore injection site for 1 to 2 days occurs in 50%, with limited use of the arm in 15%.
• Mild fever occurs in 4%, headache in 40% and joint pain in 20%
• The vaccine never causes meningitis.
9. Mumps or Rubella Vaccine: There are no reactions except for an occasional sore injection site.
10. Papillomavirus Vaccine:
• No serious reactions reported
• Sore injection site for few days in 80%
• Mild redness and swelling at the injection site (in 25%)
• Fever over 100.4° F (38.0° C) in 10% and fever over 102° F (39° C) in 1-2%.
• Headache in 30%
11. Pneumococcual Vaccine:
• No serious reactions
• Pain, tenderness, swelling OR redness at the injection site in 15 - 30%
• Mild fever under 102° F (39° C) in 15% for 1-2 days
12. Polio Vaccine:
• Polio vaccine by injection occasionally causes some muscle soreness.
• Oral vaccine no longer used in the U.S.
13. Rotavirus Vaccine:
• No serious reactions to this oral vaccine
• Mild diarrhea or vomiting for 1 to 2 days in 3%
• No fever 

And remember, contact your doctor if your child develops any of the "Call Your Doctor" symptoms.

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Disclaimer: This information is not intended to be a substitute for professional medical advice. It is provided for educational purposes only. You assume full responsibility for how you choose to use this information. For more information, click here.  

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