NVIC Vaccine News

Do You Know How to Recognize a Vaccine Reaction?

By Barbara Loe Fisher
Published August 27, 2018 in Government


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Do you know how to recognize a vaccine reaction?

Like with prescription drugs and other pharmaceutical products, reactions to vaccines can be mild or severe. There can be complete recovery or long lasting health problems after vaccine reactions. Rarely, vaccine reactions can be fatal. 1 2

If you are making a decision about vaccination for yourself or your child, it is important to first become fully informed about each vaccine’s reported side effects, precautions and contraindications, which means reasons for why a person may be at risk for having a serious reaction. 3 4

It is especially important for parents to become informed about vaccine complications and how to recognize the symptoms of a vaccine reaction. 5

When a person collapses within seconds, minutes or hours of vaccination, it may be anaphylactic shock – a life threatening allergic reaction like can happen after bee stings, or exposure to certain drugs, chemicals or foods like peanuts. 6 7

Signs of anaphylaxis include problems with breathing and swallowing, wheezing, chest or abdominal pain, vomiting, diarrhea, hives and rashes, swelling, weakness, mental confusion and loss of consciousness.

Depending upon the vaccine, most vaccine reactions take longer than a few minutes to develop. For example, brain inflammation reactions to pertussis (whooping cough) vaccine in the DPT or DTaP shots usually occur within 72 hours or a week of vaccination, 8 while it may take between one and two weeks for signs of brain inflammation to develop after getting live virus measles, mumps and rubella vaccine. 9

There should be careful monitoring of signs and symptoms of vaccine reactions for at least a week or two after vaccination. Look for symptoms like:

  • High fever (over 103F);
  • Skin redness or discoloration, swelling or hardened lump and pain at the site of the injection; 10 11 12
  • High pitched screaming, which is shrill inconsolable crying by babies that lasts for hours 13 14
  • Collapse/Shock, which is known as a hypotonic/hyporesponsive episode, when a child suddenly goes limp and may have pale skin or blue tinged lips 15
  • Excessive sleepiness, when a child sleeps deeply for an unusually long period of time and does not wake to eat
  • Convulsion, also known as a seizure, which may include rolling of eyes, blank staring for long periods, twitching, trembling, shaking, stiffness and jerking of the body 16 17 18 19 20
  • Brain inflammation, also known as encephalitis or encephalopathy, is the most serious vaccine complication. Depending upon the age, symptoms can include agitation, high-pitched screaming with arching of the back or inconsolable crying, convulsions, muscle weakness, paralysis, double vision, slurred speech, mental confusion and unconsciousness. 21 22 23 24 25 26 27
  • Behavior Changes and Mental or Physical Regression after vaccination can be signs of brain or immune system damage, such as loss of muscle control and developmental milestones, sleep disturbances, personality changes, onset of severe allergies and intestinal disorders or other dramatic changes in health. 28 29 30 31 32 33 34

If there is a question about whether or not brain inflammation or another type of serious reaction is occurring after vaccination, contact the person who administered the vaccine(s) and go to a hospital emergency room immediately.

The details of the health problems experienced after vaccination should be entered into the permanent medical record and reported to the federal Vaccine Adverse Event Reporting System. 35

If a doctor or medical worker will not make a vaccine reaction report to the government, you can make a report yourself. 36

At NVIC.org, learn more about vaccines, diseases and the human right to informed consent to medical risk taking.

Empower yourself today with well-referenced information that can help you make educated decisions about vaccination.

It’s your health. Your family. Your choice.


1 Centers for Disease Control (CDC). Possible Side Effects from Vaccines.

2 Food and Drug Administration (FDA). Vaccines Licensed for Use in the United States (Manufacturer Product Information Package Inserts).

3  CDC. Vaccine Recommendations of the ACIP: Contraindications and Precautions.

4 Food and Drug Administration (FDA). Vaccines Licensed for Use in the United States (Manufacturer Product Information Package Inserts).

5 National Vaccine Information Center. If You Vaccinate, Ask 8.

6  U.S. National Library of Medicine. Anaphylaxis (Anaphylactic Shock). MedLine Plus.

7  CDC. Preventing and Managing Adverse Vaccine Reactions.  Feb. 21, 2018.

8  Institute of Medicine Committee to Study New Research on Vaccines. DPT Vaccine and Chronic Nervous System Dysfunction: A New Analysis. Executive Summary (pp.1-2) Washington, D.C. The National Academies Press 1994.

9  Millichap JG. Measles Vaccine and Encephalopathy. Pediatric Neurology Briefs 1998; 12(3): 22.

10 Pineau A, Durand C et al. Role of aluminum in skin reactions after diphtheria-tetanus-pertussis-poliomyelitis vaccination: an experimental study in rabbits. Toxocology 1992; 73(1): 117-125.

11 Pichichero ME, Edwards KM et al. Safety and Immunogenicity of Six Acellular Pertussis Vaccines and One Whole-Cell Pertussis Vaccine Given as a Fifth Dose in Four to Six Year old Children. Pediatrics 2000; 105(1).

12  Donaldson S, Canavan T et al. Injection Site Necrosis and Ulceration Following Vaccination in an Adult Patient. JDD 2018; 17(3).

13 Markel H, Oski JA et al. The Crying Infant. In: The Portable Pediatrician 1992; pp.70-72.

14 Neuroimmunolgy Clinic, KK Women’s and Children’s Hospital. Encephalitis in Children: Symptoms, Complications and Treatment. Health Xchange 2016.

15 DuVernoy TS, Braun MM, the VAERS Study Group. Hypotonic-Hyporesponsive Episodes Reported to the Vaccine Adverse Event Reporting System (VAERS), 1996-1998. Pediatrics 2000; 106(4).

16  Wheless JW, Sirven JI. Seizures in Newborns. Epilepsy Foundation Aug. 27, 2013.

17  Sun Y, Christensen J et al. Risk of febrile seizures and epilepsy after vaccination with diphtheria, tetanus, acellular pertussis, inactivated poliovirus and Haemophilus influenzae type B. JAMA 2012; 307(8): 523-531.

18  Duffy J, Weintraub E et al. Febrile Seizure Risk After Vaccination in Children 6 to 23 Months. Pediatrics 2016; 138(1).

19  Wolf SM, Forsythe A. Epilepsy and mental retardation following febrile seizures in childhood. Acta Pediatr Scand 1989; 78(2): 291-295.

20 MacDonald BK, Johnson AL et al. Febrile convulsions in 220 children – neurological sequelae at 12 years follow-up. Eur Neurol 1999; 41(4): 179-186.

21 LaRoche SM. Seizures and Encephalopathy. Semin Neurol 2011; 31(19): 194-201.

22 HRSA. Encephalopathy, Encephalitis, Acute Dissemination Encephalomyelitis. Vaccine Injury Compensation Program Vaccine Injury Table. Mar. 21, 2017.

23 Pellegrino P, Carnovale C, Perrone V et al. Acute Disseminated Encephalomyelitis Onset: Evaluation Based on Vaccine Adverse Events Reporting System. PLOS One Oct. 18, 2013.

24 Alicino C, Infante MT et al. Acute disseminated encephalomyelitis with severe neurological outcomes following virosomal seasonal influenza vaccine. Hum Vaccin Immunother 2014; 10(7).

25 Rao S, Elkon B et al. Long-Term Outcomes and Risk Factors Associated with Acute Encephalitis in Children. J Ped Infect Dis Soc 2015; 1(1): 20-27.

26  Iro MA, Sadarangani M et al. ImmunoglobuliN in the Treatment of Encephalitis (IgNiTE): protocol for a multicenter randomized controlled trial. BMJ Open 2016; 6(11).

27 Burton KLO, Williams TA et al. Long-Term Neuropsychological Outcomes of Childhood Onset Acute Disseminated Encephalomyelitis (ADEM): A Meta-Analysis. Neuropsychology Rev 2017; 27(2): 124-133.

28 Institute of Medicine Committee to Study New Research on Vaccines. DPT Vaccine and Chronic Nervous System Dysfunction: A New Analysis. Executive Summary (pp.1-2) Washington, D.C. The National Academies Press 1994.

29 Thompson NP, Montgomery SM. Is measles vaccination a risk factor for inflammatory bowel disease? Lancet 1995; 345(8957): 1071-1074.

30 Hurwitz E, Morgenstern H. Effects of diphtheria-tetanus-pertussis or tetanus vaccination on allergies and allergy-related respiratory symptoms among children and adolescents in the United States. J Manipulative Physiol Ther 2000; 23(2): 81-90.

31 Enriquez R, Addington W et al. The relationship between vaccine refusal and self reports of atopic disease in children. J Allergy Clin Immunol 2005; 115(4): 737-744.

32 Mawson AR, Ray BD, Bhuiyan AR, Jacob B. Pilot comparative study on the health of vaccinated and unvaccinated 6-to-12-year-old US children. J Trans Sci 2017; 3(3): 1-12.

33 Rismanchi N, Gold JJ et al. Neurological Outcomes After Presumed Childhood Encephalitis. Pediatr Neurol 2015; 53(3): 200-206.

34 Matsubara Y, Osaka H et al. Long-term outcomes in motor and cognitive impairment with acute encephalopathy. Brain Dev 2018; 40(9): 801-812.


35 NVIC. Report Vaccine Reactions: It’s the Law!

36 DHHS. Vaccine Adverse Event Reporting System (VAERS). Two Ways to Submit an Online Report to VAERS. Also Online VAERS Reporting Demonstration. July 2017.

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9 Responses to "Do You Know How to Recognize a Vaccine Reaction?"
Commenter Name
Donna Dement
Posted: 9/3/2018 9:50:52 AM
Love this important article! Would love to see the oft seen breathing problems in the bullet points. Above the bullet points I do see anaphylaxis mentioned and wheezing... which I feel, at least in our case, was most common. Breathing difficulty and inflammation which with time leads to pneumonia, and/or bronchitis. Also Ear Infections are rampant after receiving vaccines it seems. Thank you for ALL you do and have done over the years!!
Commenter Name
L Smith
Posted: 10/18/2018 7:29:43 PM
Well, just hope you dont live in Mississippi because we only have medical exemptions in this state, and you won’t get one of those even if your child has seizures, high fever, rashes, loss of skills, etc after a vaccine. If you are lucky enough to finally get a pediatrician to give you an exemption, you just hope that your child hasn’t been permenantly damaged already. In this state- none of the above mentioned side effects can be caused by vaccines. NO- one size fits all and vaccines are always safe in Mississippi!
Commenter Name
Carol Schwab
Posted: 11/28/2018 8:06:55 PM
This was a great article for signs of babies/children, but what about adults? What are signs to look for in the elderly, who may not vocalize a problem because they don't want to be a bother/embarrassed or are impaired because of Alzheimer's? If you ha e an article on the elderly and immunizations, please direct me. You have great info!
Commenter Name
janice curtin
Posted: 12/27/2018 7:59:59 AM
I would like to see you expand on this. Add: baby quick death (SIDS) pancreatitis, born with developmental problems, due to moms shots in utero, auto immune illness due to imbalanced TH1 andTH2 immune system, child won't eat, slow in language development, early in sexual development, behavior problems, violence, Chrones, Colitis, restless leg syndrome, paralysis. These are the problems I see in vaccinated children. Most parents have no idea that most of their children's health and behavior issues are from vaccines. Metals in them just play havoc in the body. You cannot take up nutrients properly or detox well. If people knew the effects of vaccines on their own children, we would have many more on our side. No child with metals in him/her escapes problems.
Commenter Name
Haley Culbertson
Posted: 1/4/2019 3:44:30 PM
I wish I had researched this before vaccinating both my children. My oldest is 4 and youngest is 13 months. My oldest hasn’t had shots since the 18 month check up, and my youngest had shots up to 6 months plus the flu shot (just once) at 9 months before I finally wisened up and researched vaccines the last few months. Never again will my kids have shots. I have an exemption (TX), but cannot find a pediatrician who will take us without vaccinating. Ours kicked us out of the practice. I’ve gone down the lists on anti vaccine websites and called those doctors but mostly they’re not accepting new patients or they don’t take insurance. Any ideas, I’m in Houston, Tx?? Also- how can I detox my 4 year old and 13 month old from the metals and other toxins in the vaccines they’ve had?? Help!
Commenter Name
Posted: 2/12/2020 10:44:38 PM
What about adults or older children if there's not a high pitch scream. Like what would that look like if we couldn't describe what was happening but not crying like that. Editors note: For affected older children, head banging is a symptom. For adults, symptoms of encephalopathy include changes in personality, difficulties concentrating or focusing, problems with memory, lethargy. They can also have neurological symptoms that present as muscle weakness, difficulties with speech, involuntary muscle movement. If things progress, adults can become very disorientated and this can even lead to coma. I hope this is helpful.
Commenter Name
Posted: 2/25/2021 5:18:24 PM
I wonder, how long after a vaccine can symptoms start to show? Can it be a year later? My previously unvaccinated granddaughter moved in with her dad, who took her to get her MMR vaccine. It's been since spring/summer of 2020, and she's had two seizures in as many days (one yesterday and one today - 2/24/21 & 2/25/21). No illness or infection, previously. She's never had one before (she's 5). The MMR package insert lists fibral/afibral seizures as an adverse reaction. It makes me question if it could be this long afterward. It's breaking my heart.
Commenter Name
Posted: 7/8/2022 4:53:49 AM
Commenter Name
Posted: 4/25/2023 7:16:17 AM
In my experience vaccines reactions can also take months or even year after. It has a profound impact in the Natural immune system and in the gut's microbiome. So not only it can take a matter of minutes, hours or two weeks but long time after as well, this is the reason many parents cant link it from vaccines, it took me 3 years to realised what I have done to my child after his first year vaccination programme, luckily I learned how to detox in time and my child is thriving but I never stop questioning what other effects will have when he gets older if his diet isn't ideal or perfect because already I cut off gluten and pasteurised dairy, meaning some how his immune system is been effected to not be able to process things that me and his dad and the rest of his family have no problem with.

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