Immunization Reactions
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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
When to Call for Immunization Reactions
Call 911 Now- Trouble breathing or swallowing
- Not moving or very weak
- Can't wake up
- You think your child has a life-threatening emergency
Call Doctor or Seek Care Now- Fever in baby less than 12 weeks old. Caution: do NOT give your baby any fever medicine before being seen.
- Fever over 104° F (40° C)
- Fever after vaccine given and weak immune system (such as sickle cell disease, HIV, cancer, organ transplant, taking oral steroids)
- Crying nonstop lasts more than 3 hours
- Rotavirus vaccine followed by vomiting or severe crying
- Your child looks or acts very sick
- You think your child needs to be seen, and the problem is urgent
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Contact Doctor Within 24 Hours- Redness around the shot becomes larger and more painful to touch after 3 days
- Fever lasts more than 3 days
- Fever returns after being gone more than 24 hours
- Measles vaccine rash (starts day 6 to 12 after shot) lasts more than 4 days
- You think your child needs to be seen, but the problem is not urgent
Contact Doctor During Office Hours- Redness or red streak around shot is larger than 2 inches (5 cm)
- Redness, swelling or pain is getting worse after 3 days
- Fussiness from vaccine lasts more than 3 days
- You have other questions or concerns
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Self Care at Home- Normal immunization reaction (mild redness and swelling, fever)
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Call 911 Now
- Trouble breathing or swallowing
- Not moving or very weak
- Can't wake up
- You think your child has a life-threatening emergency
Call Doctor or Seek Care Now
- Fever in baby less than 12 weeks old. Caution: do NOT give your baby any fever medicine before being seen.
- Fever over 104° F (40° C)
- Fever after vaccine given and weak immune system (such as sickle cell disease, HIV, cancer, organ transplant, taking oral steroids)
- Crying nonstop lasts more than 3 hours
- Rotavirus vaccine followed by vomiting or severe crying
- Your child looks or acts very sick
- You think your child needs to be seen, and the problem is urgent
Contact Doctor Within 24 Hours
- Redness around the shot becomes larger and more painful to touch after 3 days
- Fever lasts more than 3 days
- Fever returns after being gone more than 24 hours
- Measles vaccine rash (starts day 6 to 12 after shot) lasts more than 4 days
- You think your child needs to be seen, but the problem is not urgent
Contact Doctor During Office Hours
- Redness or red streak around shot is larger than 2 inches (5 cm)
- Redness, swelling or pain is getting worse after 3 days
- Fussiness from vaccine lasts more than 3 days
- You have other questions or concerns
Self Care at Home
- Normal immunization reaction (mild redness and swelling, fever)
Care Advice for Immunization Reactions
Treatment for Common Immunization Reactions
- 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.
- 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.
- 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.
- 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.
- 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
- 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).
- 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.
- 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.
- Hemophilus Influenza Type B Vaccine (Hib):
- No serious reactions reported.
- Sore injection site or mild fever only occurs in 2% of children.
- 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.
- 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.
- 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.
- 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
- 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.
- Mumps or Rubella Vaccine (part of MMR):
- There are no serious reactions.
- Sometimes, a sore shot site can occur.
- 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%.
- 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.
- 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.
- 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.
- 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.
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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