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 Us 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

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.