Immunization Reactions

Is this your child's symptom?

• Reactions to a recent immunization (vaccine)
• Most are reactions at the shot site (such as pain, swelling, redness)
• General reactions (such as a fever or being fussy) may also occur

Reactions to These Vaccines are Covered:

• Chickenpox (varicella) virus
• COVID-19 virus
• DTaP (Diphtheria, Tetanus, Pertussis)
• Hemophilus influenzae type b
• Hepatitis A virus
• Hepatitis B virus
• Human Papilloma virus
• Influenza virus
• MMR (Measles, Mumps, Rubella)
• Meningococcal
• Polio virus
• Pneumococcal
• Rotavirus
• Tuberculosis (BCG vaccine)

Symptoms of Vaccine Reactions

• Local Reactions. 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.
• Fever. Fever with most vaccines begins within 24 hours and lasts 1 to 2 days.
• Delayed Reactions. With the MMR and chickenpox shots, fever and rash can occur. These symptoms start later. They usually begin between 1 and 4 weeks.
• Anaphylaxis. Severe allergic reactions are very rare. They start within 20 minutes. Sometimes can occur up to 2 hours after the shot. Vaccine health workers know how to treat these reactions.

Vaccine Free App

• Vaccines on the Go app from Children's Hospital of Philadelphia
• This free app can answer any vaccine questions you may have
• It is fact-based and up-to-date

When to Call for Immunization Reactions

Care Advice for Immunization Reactions

Treatment for Common Immunization Reactions

1. What You Should Know About Common Shot Reactions:
   • Immunizations (vaccines) protect your child against serious diseases.
   • Pain, redness and swelling are normal where the shot was given. Most symptoms start within the first 12 hours after the shot was given. Redness and fever starting on day 1 or 2 of the shot is always normal.
   • All of these reactions mean the vaccine is working.
   • Your child's body is making 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 doctor for normal reactions, such as redness or fever.
   • Here is some care advice that should help.
2. Vaccine Site Reaction: Treatment
   • Some pain, swelling and skin redness at the injection site is normal. It means the vaccine is working.
   • Massage: gently massage the injection site 3 or more times a day.
   • Heat: for pain or redness, apply a heating pad or a warm wet washcloth to the area for 10 minutes. Repeat as needed. Reason: will increase blood flow to the area. May apply cold if you prefer, but avoid ice.
   • No Pain Medicine: try not to give any pain medicines. Reason: pain medicines may reduce the body’s normal immune response. Use local heat instead. Pain rarely becomes bad. If needed, use acetaminophen.
   • Hives at the Shot Site: if itchy, can put on 1% hydrocortisone cream (such as Cortaid). No prescription is needed. Use twice daily as needed.
3. Fever with Vaccines: Treatment
   • Fever with vaccines is normal, harmless and probably helpful. Reason: fever speeds up your body's immune system.
   • Fever with most vaccines begins within 12 hours and lasts 1 to 2 days.
   • For low grade fevers of 100-102° F (37.8 to 39° C), do not give fever medicines. Reason: they may reduce your body’s normal immune response.
   • For fevers above 102° F (39° C), medicine may be given for discomfort. If needed, use acetaminophen.
   • Fluids. Encourage cool fluids in unlimited amounts. Reason: prevent dehydration. Fluids can also lower high fevers. For infants age younger than 6 months, only give formula or breastmilk.
   • Clothing. Dress in normal clothing. For shivering or the chills, use a blanket until it stops.
4. General Symptoms From Vaccines:
   • All vaccines can cause mild fussiness, crying and restless sleep. This is usually due to 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.
   • They will usually go away in 24-48 hours.
5. Call Your Doctor If:
   • Redness becomes larger than 2 inches (5 cm)
   • Redness becomes more painful after 3 days
   • Fever starts after 2 days (or lasts more than 3 days)
   • Redness or pain lasts more than 7 days
   • You think your child needs to be seen
   • Your child becomes worse

Specific Immunization Reactions

1. Chickenpox Vaccine:
   • Pain or swelling at the shot site for 1 to 2 days. (20% of children)
   • Mild fever lasting 1 to 3 days begins 14 to 28 days after the shot (10%). Give acetaminophen or ibuprofen for fever over 102° F (39°C).
   • Never give aspirin for fever, pain or within 6 weeks of getting the shot. Reason: Risk of Reye syndrome, a rare but serious brain disease.
   • Chickenpox-like rash (usually 2 red bumps) at the shot site (3%)
   • Chickenpox-like rash (usually 5 red bumps) scattered over the body (4%)
   • This mild rash begins 5 to 26 days after the shot. Most often, it lasts a few days.
   • Children with these rashes can go to child care or school. Reason: For practical purposes, vaccine rashes are not spread to others.
   • Exception: Do not go to school if red bumps drain fluid and are widespread. Reason: can be actual chickenpox.
   • Caution: If vaccine rash contains fluid, cover it with clothing. You can also use a bandage (such as Band-Aid).
2. COVID-19 Vaccine
   • Injection site reactions. Pain and tenderness starts within 8 hours (90% of patients). Other local reactions are some swelling (10%) or skin redness (5%). Local symptoms usually last 1 to 3 days.
   • General body symptoms after the second dose. Fever (15%), chills (40%), tiredness (70%), muscle aches (50%) and headaches (60%). Runny nose and sore throat are more common with Omicron variant. Some other mild side effects are decreased appetite, nausea, dizziness, and increased sleep.
   • General symptoms start at about 24 hours. They usually last 1 day, sometimes 2.
   • Vaccines with 2 doses. Symptoms are more frequent after the 2nd vaccine.
   • Vaccines with one dose. Side effects were the same type, but a little less often.
   • Booster shots. Side effects much the same.
   • The vaccine does not cause any respiratory symptoms such as cough, runny nose, sore throat or shortness of breath.
   • It is impossible to get COVID-19 from the vaccine. Reason: there is no live COVID-19 virus in the vaccine.
   • Severe allergic reactions to the vaccine are very rare.
3. Diphtheria, Tetanus, Pertussis (DTaP) Vaccine:
   • The following harmless reactions to DTaP can occur:
   • Pain, tenderness, swelling and redness at the shot site are the main side effects. This happens in 25% of children. It usually starts within the first 12 hours. Redness and fever starting on day 1 of the shot is always normal. It lasts for 3 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.
   • Large swelling over 4 inches (10 cm) can follow the later doses of DTaP. The area of redness is smaller. This usually occurs with the 4th or 5th dose. It occurs in 5% of children. Most children can still move the leg or arm normally.
   • The large thigh or upper arm swelling goes away without treatment by day 3 (60%) to day 7 (90%).
   • This is not an allergy. Future DTaP vaccines are safe to give.
4. Hemophilus Influenza Type B Vaccine (Hib):
   • No serious reactions reported.
   • Sore injection site or mild fever only occurs in 2% of children.
5. Hepatitis A Vaccine:
   • No serious reactions reported.
   • Sore injection occurs in 20% of children.
   • Loss of appetite occurs in 10% of children.
   • Headache occurs in 5% of children.
   • Most often, no fever is present.
   • If these symptoms occur, they most often last 1-2 days.
6. Hepatitis B Virus Vaccine (HBV):
   • No serious reactions reported.
   • Sore shot site occurs in 30% of children and mild fever in 3% of children.
   • Fever from the vaccine is rare. Any baby under 2 months with a fever after this shot should be examined.
7. Influenza Virus Vaccine:
   • Pain, tenderness or swelling at the injection site occurs within 6 to 8 hours. This happens in 10% of children.
   • Mild fever under 103° F (39.5° C) occurs in 20% of children. Fevers mainly occur in young children.
   • Nasal Influenza Vaccine: Congested or runny nose, mild fever.
8. Measles Vaccine (part of MMR):
   • The measles shot can cause a fever (10% of children) and rash (5% of children). This occurs about 6 to 12 days after the shot.
   • 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 needed. The rash cannot be spread to others. Your child can go to child care or to school with the rash.
   • Call Your Doctor If:
     • Rash changes to blood-colored spots
     • Rash lasts more than 3 days
9. Meningococcal Vaccine:
   • No serious reactions.
   • Sore shot site for 1 to 2 days occurs in 50%. Limited use of the arm occurs in 15% of children.
   • Mild fever occurs in 5%, headache in 40% and joint pain in 20%
   • The vaccine never causes meningitis.
10. Mumps or Rubella Vaccine (part of MMR):
    • There are no serious reactions.
    • Sometimes, a sore shot site can occur.
11. Papillomavirus Vaccine:
    • No serious reactions.
    • Sore injection site for few days in 90%.
    • Mild redness and swelling at the shot site (in 50%).
    • Fever over 100.4° F (38.0° C) in 10% and fever over 102° F (39° C) in 2%.
    • Headache in 30%.
12. Pneumococcal Vaccine:
    • No serious reactions.
    • Pain, tenderness, swelling or redness at the injection site in 20%.
    • Mild fever under 102° F (39° C) in 15% for 1-2 days.
13. Polio Vaccine:
    • Polio vaccine given by shot sometimes causes some muscle soreness.
    • Polio vaccine given by mouth is no longer used in the U.S.
14. Rotavirus Vaccine:
    • Most often, no serious reactions to this vaccine given by mouth.
    • Mild diarrhea or vomiting for 1 to 2 days in 3%.
    • No fever.
    • Rare serious reaction: intussusception. Risk is 1 in 100,000 (CDC). Presents with vomiting or severe crying.
15. BCG Vaccine for Tuberculosis (TB):
    • Vaccine used to prevent TB in high-risk groups or countries. It is not used in the US or most of Canada. Note: This is different than the skin test placed on the forearm to detect TB.
    • BCG vaccine is given into the skin of the right shoulder area.
    • Timing: Mainly given to infants and young children.
    • Normal reaction: After 6 to 8 weeks, a blister forms. It gradually enlarges and eventually drains a whitish yellow liquid. The blister then heals over leaving a scar. The raised scar is proof of BCG protection against TB.
    • Abnormal reaction: Abscess (infected lump) occurs in the shoulder or under the arm. Occurs in 1% of patients.
    • Call Your Doctor If:
      • Blister turns into a large red lump
      • Lymph node in the armpit becomes large

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

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