Our Readers Report Their Side Effects to the COVID-19 Vaccine

COVID vaccine side effects
Emma Yasinski
Emma Yasinski Staff Writer

MedShadow was the first to launch its COVID-19 Vaccine Side Effect Tracker, even before any COVID-19 vaccines were authorized by the Food and Drug Administration (FDA). Its goal is to report on the adverse effects in clinical trials, help our readers make informed decisions and know what to expect when they get their shots. Experts said early on that some of the side effects may be severe enough that patients will want to stay home from work after receiving the vaccine. 

Our vaccine side effect tracker has amassed more than 800 comments, a handful of which have discussed unusual reactions, such as blurred vision and heart palpitations.

Heart and vision symptoms weren’t reported in the clinical trials and haven’t yet been the focus of any investigations published by the Centers for Disease Control and Prevention (CDC). So, MedShadow is exploring those symptoms.

A series of case studies from Switzerland reported that nine out of the first 12,349 people vaccinated there experienced a rise in blood pressure after receiving their first dose of the Pfizer or the Moderna vaccine. Some also had headaches, chest pains, sweating and anxiety. All but one of the patients reported having a history of well-controlled hypertension. Six patients required emergency treatment or monitoring, and all recovered.

One online survey reported that four out of 803 healthcare workers who replied and had received the Pfizer vaccine experienced blurred vision. Another 35 reported heart palpitations. The same research group found similar results for patients who received the Moderna vaccine. The survey had several limitations, including the fact that nearly 90% of those respondents  were women. Patients submitted their responses anonymously, and neither the researchers nor other healthcare providers evaluated their symptoms. Nor did the researchers take into account any preexisting conditions or collect data on the timing of symptoms. Lastly, the study only included participants who reported at least one symptom. Patients who experienced no adverse effects were excluded from the analyses.

We cannot firmly conclude that any of the symptoms reported in this study or in the comments from our tracker were or were not COVID vaccine side effects.

Racing Heart as Covid Vaccine Side Effects

On Feb. 6, 2021, Matt L. described having immediate heart palpitations in the comment section of MedShadow’s side effect tracker. “Within 2-3 minutes of vaccination I experienced rapid heart palpitations, which lasted a couple minutes, I thought I might die. Was it a stress reaction? I have no history of adverse reactions to vaccines. My heart rate remained elevated about 20 beats above normal for the 30 minute observation period and was still elevated and irregular that evening. I was unable to sleep. The next day my heart was back to near normal, but I had to take off work a couple days due to feeling crappy. I reported it on VAERS,” he writes.

Others, like Nick, who submitted this comment on April 8, 2021, have told of palpitations that started later and lasted longer. “I received my first dose on March 2nd and my second dose on March 30th of the Moderna vaccine. Both times about 7 days into each dose I started noticing heart palpitations. I do not have any heart disease, except controlled high blood pressure. After the first dose, they started and were happening often, and was concerning – then they stopped after 5 days right before my scheduled second shot. Now after my second dose, they have started again a week after the dose. Not sure if they are related to the vaccine, but good to see others are experiencing this symptom too. I will see my PCP next week, Hopefully, the palpitations will stop as they did after the first shot.”

Blurred Vision as Covid Vaccine Side Effects

Several others mentioned blurred vision in the days following the shot. TrudyD who writes, “Had first Pfizer shot on 3/12/2021 at 1:30pm. Woke at 6 AM next day with blurred vision in right eye. Lasted 12 hours. Am headed to ophthalmologist this week to discuss. Not many reporting blurred vision to date. I reported to cdc. I think I will wait 4-6 weeks and evaluate reports before proceeding. Event was definitely outcome of shot. I take no meds and have no conditions.”

On April 1, 2021, Sean writes, “My Moderna 2nd shot was 3/15/21. Right eye has serious blocked vision to left side, just developed 3/31. Will be scheduling Ophthalmologist visit. Will followup with results.”

Two doctors involved in administering vaccines told MedShadow that they haven’t cared for any patients with vision symptoms or heart palpitations persisting into the days after the shots. “Many patients of ours have described diverse symptoms, some with an allergic flavor (hives, rashes, for example) and some with neurologic flavor (tingling, numbness, metallic taste, even personality change!).  We have not seen [heart palpitations, elevated heart rate, blurry vision or seeing spots],” Kimberly Blumenthal MD, an allergist, immunologist and drug allergy researcher at Massachusetts General Hospital, who published some of the first accounts of delayed arm pain, writes in an email.

Kartik Cherabuddi, MD, an infectious disease expert at the University of Florida also hadn’t noticed these lingering symptoms in his patients, but added that if the symptoms emerged almost immediately after vaccination, “that would be expected with a vasovagal presyncope/syncope; [Fainting or feeling like you’re going to faint] and the heart palpitations can be seen as part of an allergic response as well.”

What is Syncope?

Syncope is a medical term for fainting, and presyncope describes the sensations that can suggest you may faint, even if you don’t end up losing consciousness, or feeling lightheaded. If you do faint, you’ll likely regain consciousness within a minute. There are many reasons you may have a syncopal episode. They include dehydration, stress, irregular heartbeats, exhaustion, low blood sugar or standing up too fast. A syncopal episode can be a symptom of heart disease or even a side effect of drugs like diuretics, calcium antagonists, ACE inhibitors, nitrates, antipsychotics, antihistamines, levodopa, opioids and alcohol.

If you are otherwise healthy, syncope and presyncope can still be caused by situational triggers, like prolonged standing, anxiety or the sight of blood. The symptoms of presyncope include:

  • Nausea
  • Vision disturbances
  • Lightheadedness
  • Sweating
  • Rapid heartbeat
  • Weakness
  • Shakiness
  • Changes in body temperature (feeling hot or cold)
  • Vertigo

What to Do

Syncope can be scary, but it is rarely a life-threatening experience. People generally recover from it in mere minutes to hours.

If you do faint, do not stand up right away when you regain consciousness, as this can cause you to faint again. The National Institutes of Health recommend that you remain lying down for at least 10 to 15 minutes and then get up slowly. If you feel signs of presyncope, it’s best to sit or lie down so that you’ll be safe if you’re likely to fall. You can also lower your head between your knees to encourage blood flow to your brain.

If you experience syncope regularly, see your doctor. He or she can conduct blood tests and order an image of your heart to rule out underlying causes. Depending on the results , your healthcare provider may suggest a change in diet, biofeedback, elevating your head while you sleep or even surgical treatments, such as implanting a pacemaker.

 [Editor’s note: We do not verify the reports we receive in comments, nor does MedShadow’s comment section serve as an official means to report side effects to agencies monitoring vaccine safety. If you experience adverse effects, be sure to report them to VAERS or to the V-SAFE app designed for COVID-19 vaccinations and see your healthcare provider. MedShadow chose to recount the comments by readers on its side tracker verbatim and not to correct them for grammar or style.] 



DISCLAIMER: MedShadow provides information and resources related to medications, their effects, and potential side effects. However, it is important to note that we are not a substitute for professional medical advice, diagnosis, or treatment. The content on our site is intended for educational and informational purposes only. Individuals dealing with medical conditions or symptoms should seek guidance from a licensed healthcare professional, such as a physician or pharmacist, who can provide personalized medical advice tailored to their specific circumstances.

While we strive to ensure the accuracy and reliability of the information presented on MedShadow, we cannot guarantee its completeness or suitability for any particular individual's medical needs. Therefore, we strongly encourage users to consult with qualified healthcare professionals regarding any health-related concerns or decisions. By accessing and using MedShadow, you acknowledge and agree that the information provided on the site is not a substitute for professional medical advice and that you should always consult with a qualified healthcare provider for any medical concerns.

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Danice Hertz

I experienced severe paresthesias in my face, chest wall and limbs starting 30 minutes after receiving the first dose of the Pfizer covid vaccine. These symptoms have progressed over the past 18 weeks and I am being worked up for small fiber neuropathy and mast cell activation syndrome. I have a group of 75 people with similar reactions. There are clearly neurological reactions to these vaccines and they need to be publicized and studied so that we can get help.

Michael Todd

The night of and the day after receiving the second Moderna dose my wife and I were quite sick. Chills, headaches and fevers. We expected that. What we didn’t expect was that four weeks after receiving my second dose of the Moderna Vaccine the skin on my hands started to crack and blister and the skin started to peel off. That process lasted about 2-3 weeks. Shortly after my hands “healed” it started happening to my feet. Several places the skin cracked open and bled and, like my hands, the skin started peeling off in layers. There was no pain with the peeling skin but the open cracks and bleeding were quite painful. I’ve never had this happen before and I’m 74 years old. It has left my skin very dry and itchy feeling. My wife didn’t have the same peeling issue but her skin has also become dry and itchy. Nothing else in our diet or routine has changed. What else is this experimental treatment doing in our bodies?

Irene Au

I have also been experiencing heart palpitations since I got my first dose of Pfizer. I just got my second dose yesterday and the heart palpitations continue. At first I did not connect the dots that it was related to the vaccine, but I am sure that it is. I also experience shortness of breath from time to time. I am otherwise in top shape and am usually healthy. I hope these palpitations go away soon! Curious to know if there is any remedy or advice for me? Since this seems to be a lesson common reaction, I haven’t been able to find much information, and my own PCP has little advice to offer.

Savoy IL

Yes, a lot of people are reporting experiencing a delayed vertigo several weeks after the first shot. Possibly an autoimmune response in the inner ear during the antibody forming phase of the vaccination process. It seems most are getting completely ignored by the medical community. I has some mild to moderate dizziness two and a half weeks after the Pfizer vaccine that slowly dissipated over the next 3 weeks. I had a Meniere’s Attack in 2006 and believe my body is prone to this. It also reactivated my psoriasis on my scalp the exact same way I get a few weeks after the annual flu shot in the fall. The doctors all tell me that “it’s the change in weather, not the flu shot” Strange now I get it in the spring a few weeks after another vaccination? I’m on Humira for another condition so I imagine without that anti inflammatory the reaction I had could have been much worse. My brother developed psoriasis after the Anthrax vaccine, I suspect these Covid Vaccines are quite potent and auto inflammatory inducing just like the Anthrax one.


Right after getting the Moderna second shot I experienced chills, sensitivity in the underarm area, breast sensitivity, and was very tired and weak. After about 10 to 14 days the symptoms went away and I felt like myself again. But then a week after that (three weeks after the 2nd shot) I woke up at night twice with my heart racing, and didn’t sleep the rest of the night. I also had tightness in the chest around the breastbone, nausea, less appetite, chills, cough, and was very thirsty. These symptoms persist still, and every time I go up the stairs in my house I’m out of breath. I can only walk very slowly now. My heart will race at random times, and I feel it beating in my throat. My chest feels like it has something in it. It is worse at night and I wake up every morning feeling very tired. When I went to urgent care, my pulse was 91, EKG was normal, oxygen saturation was very good, blood pressure was very good, and my temperature normal. I can’t help but associate all these symptoms with the vaccine.


I just got the first moderna shot today and within the 20 minutes I sat waiting to leave Walmart I got really dizzy then it passed. Then walking out to my car I had to hold on to my husband I thought it was just wearing the mask so long and I needed fresh air but then the heart palpitations started and the dizziness that comes in waves and some shaking uncontrollably as if I was cold but I wasn’t( this only lasted about 15-20 minutes) and I was nauseated for around five hours then my ears felt like there was a lot of pressure and burning in them about two hours later It’s subsided but I keep getting a weird feeling in my chest every now and again and when I check my fit bit even though I’m laying down and usual heart rate is around 60 it’s been between 70-89 all evening. Other than that I have a sore spot in my left leg that wasn’t there before and the muscle I got the injection in is a bit sore.


I received my Pfizer vaccine on 5 weeks ago and immediately afterward I had a small rash in the cubital fossa (elbow crease) on both arms. Within two hours after my vaccine I experienced nausea and fatigue. On day 3 after the vaccine I started to experience heart palpitations with increased heart rate up to 170 bpm, high blood pressure, vision disturbances such as tunnel vision and eye floaters. Although these symptoms have decreased over time, I do experience episodes of recurrence. It’s a bit scary when the episodes occur and I’ve talked to a cardiologist and ophthalmologist and all exams and tests were normal. I am healthy with normally low blood pressure, no heart issues. I have never felt so bad before.

Last edited 3 years ago by Jos

Two days after I got my second Moderna shot I started experiencing heart palpitations. I have never had any heart issues or blood pressure issues. I am going to check with my PCP just in case


I had my 2nd Pfizer dose 3.5 weeks ago. I experienced heart palpitations two nights after the second dose as well as the following morning, and after that I felt fine. Jump ahead to last night and the palpitations are back. I mostly notice them when I lie down and even wake up with them in the morning. I’m really hoping this goes away soon. I have controlled hypertension.

Gen Albert

Got my 1st Pfizer shot yesterday at 1pm, my body start feeling anxious around 6pm and had a mild tachycardia right after for 1 hour. Today i feel great and normal, and sleep well all night.


I had frightening heart pain that lasteed 2 days starting six hours after first Moderna, metallic taste, mumbness than came and went, burning, tingling nerves, a short bout of paralysis and two small seizures after having my breating seize up- it has all terrified me- i dont know if i can safely take the second shot, the arm pain and headache were not a concern at all, the rest of it has been terrifying, but I cant find any data on if I am in danger from a second shot or need medical care in some way I dont know what to do

V Shen

I started having heart palpitations a couple of days after my first shot of Pfizer vaccine. Now it’s been 6 weeks and my symptoms are getting worse and more frequent. This caused a lot of anxiety to me and seriously affected my lifestyle. When I asked a couple of doctors, they all say there’s too little evidence to support it’s vaccine related, and one did say it’s possible but still recommend me to get my second shot. My mother had similar reaction but she recovered within 2 months…I dread for my second shot, and I don’t want my mother to get her second shot either…really wish there’s more research on this or at least any treatment available.


After getting the second does of the Moderna vaccine, within 4 days I had heart palpitations. they were keeping me up at night and bothering all day long. I went to my heart doctor who gave me a halter heart monitor to where for a week. Even though I was feeling the palpitations, they stated that nothing was showing up on the halter heart monitor, but they did say that the feeling I was having was most likely from the vaccine. I found this to be very strange. Now If they have a booster I am not sure if I should get it or not after experiencing these palpitations. They lasted approx. about three weeks. I don’t know why they are ignoring these side affects in older adults. This could be the heart inflammation that they are seeing in young people.


Madame-Cure, a Gone Awry: Novel virus broke onto the scene/Oh my! It is so very mean!/Pandemic ensued/Remedy pursued/An antagonistic hack/bare arms – bodies attacked!//Sad news went excused/Just the regular dues/Paid the price for the Greater Good/The injured were heard/Through the neighborhoods/But achieved was immunity-herd//The damaged cried, Did you know that it could?!/And wished for a cure/For the cure/To occur… – Firebrand

Brenda Ann Mcdonald

My husband got a migraine after his second Moderna vaccine . Headache subsided but still has flashes of blurry vision in his left eye- lower field of vision. It is worse at night. Been to his doctor, optometrist, 2 ophthalmologist’s (one a retina specialist) and now waiting to see a neurologist. Not a debilitating problem- still drives, but really would like to have it go away! Has a call scheduled for next Tuesday to talk to Mayo to see if they will see him.


Danice, may I join your group too?

Last edited 2 years ago by Bettina

After receiving 2nd Moderna vaccine I started to blurred vision. It has not cleared. Up until that point my vision was fine.


I started to get palpitations about ten hours after my Pfizer booster. A few hours later, my chest started to feel achey and tight. I eventually got through to 111 (national UK helpline for non-urgent medical queries – this no mean feat during the current Omicron situation!). They told me to go straight to my nearest hospital A&E (accident and emergency). I had an electrocardiogram and blood tests and they said everything looked OK and it was probably just a rare side effect. It’s four days later and I’m still not quite right. Each day, I’m still getting occasional palpitations, chest tightness and some breathlessness. Since then, I’ve heard from three friends who experienced similar. I have recorded my experience on the Yellow Card scheme website (official UK scheme for monitoring drug safety). I hope this gets looked into, as clearly, it’s an issue. I’d be scared of having another booster after this, to be honest.