• COVID-19

A Definitive Guide to Possible COVID-19 Vaccine Side Effects

Vaccines are one of the best lines of defense that our bodies have against diseases – especially for newer viruses like COVID-19.

As of January 2024, over 13 billion COVID-19 vaccines have been administered worldwide.

While the thought of potentially experiencing side effects after receiving your COVID-19 shot can be stressful, these side effects are usually completely normal and harmless.

The CDC states that 92% of side effects reported after having received the COVID-19 vaccine were mild and non-life-threatening.

In fact, side effects are a great indication that our immune systems are working to produce antibodies and are activating other immune cells to fight off what it thinks is an infection.

The COVID-19 vaccine isn’t a live virus vaccine. This means that you’re not injected with the virus but rather with synthetic spike proteins.

This article will take a closer look at common and rare side effects of the COVID-19 vaccine, as well as steps you can take to alleviate your symptoms.

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How Do Vaccines Work?

Vaccines introduce the body to synthetic versions of diseases and viruses.

These versions aren’t the real thing, but rather act as a blueprint that can help the body produce antibodies against the disease.

When the antigen or vector virus is injected into the body, it triggers an immune response where the body starts developing antibodies to protect itself from harmful organisms.

Some vaccines require two or more shots to allow antibodies to develop memory cells. This is a way of training the body to acquire a long-term response to a particular disease.

When the real virus infects the body, the vaccine has helped the body be ready to protect itself.

What are the Common Side Effects of the COVID-19 Vaccine?

Side effects after a COVID-19 vaccination shot are common but tend to be mild and temporary.

They will usually resolve within two to three days without any medical treatment. Common side effects of the COVID-19 vaccine include:

• Pain

• Redness

• Swelling on the arm where you got your injection 

• Tiredness 

• Headaches 

• Muscle pain 

• Chills 

• Nausea 

• Fever 

• Mild flu-like symptoms 

• Diarrhea

Younger children and teenagers may also be susceptible to:

• Sleepiness

• Irritability or crying 

• Loss of appetite 

• Chills

Although these side effects usually only cause mild discomfort, it’s always recommended to speak to your healthcare provider if you are concerned about any of your symptoms.

Why Does the COVID-19 Vaccine Cause Side Effects?

When you typically receive a vaccine, you’re injected with antigens, which are weakened or inactive parts of a particular disease. This prompts an immune system response to make antibodies to protect you against the disease.

With the COVID-19 vaccine — and other mRNA vaccines — the antigen is a synthetic version of the virus called a vector virus. In other words, live viruses are not used in any of the COVID-19 vaccines.

It’s important to note that none of these synthetic viruses are live organisms and can’t infect us with the actual COVID-19 virus. They also aren’t able to change our DNA or affect the makeup of our body.

This antigen helps the body to create pieces of spike proteins that trigger an immune response that produces antibodies and helps us to fight the virus.

While the body is building its defense against a virus, it can cause some physical reactions to appear.

Does Each Vaccine Cause Different Side Effects?

There are four vaccines against COVID-19 in use in the U.S. at the moment. They have all been approved for vaccine safety and administration by the CDC and the World Health Organization (WHO).

They are:

• Pfizer-BioNTech

• Moderna 

• Johnson & Johnson 

• Novavax

Let’s take a closer look at how they compare to one another:

Pfizer-BioNTech

Pfizer-BioNTech is one of the double-dose mRNA vaccines available to most American adults.

Children and teenagers aged between six months and 15 years are also able to receive this vaccine under emergency use authorization (EUA). A booster shot is also available for vaccine recipients.

The side effects of the Pfizer-BioNTech are pain, redness, and swelling at the injection site, and common flu-like symptoms that can resolve on their own.

Adverse reactions are rare, but the FDA has added a warning label to indicate that they may occur with this vaccine.

Moderna

Moderna is another vaccine that requires two doses. This option is available to all uncompromised Americans, including teenagers and children under EUA. It also has a booster shot.

This vaccine causes similar side effects to the Pfizer-BioNTech shot and also has the same warning label that indicates the possibility of adverse reactions.

What is ‘COVID arm’?

‘COVID arm’ is a common side effect reported by people who receive the Moderna vaccination.

It’s classified by a red and blotchy rash that appears where you’ve received your injection, usually around seven days after your first dose.

The rash may last anywhere from five days to three weeks.

Although it can be unsightly, this rash doesn’t indicate any severe adverse reaction to the vaccine.

You can speak to your doctor or pharmacist about taking medication like antihistamines, which can help reduce the appearance and discomfort of ‘COVID arm.’

Johnson & Johnson

Johnson & Johnson is a single-dose vaccine available to Americans who are 18 and older or anyone who can’t get any other shot because of medical reasons. It’s recommended to get a Moderna or Pfizer-BioNTech booster.

The Johnson & Johnson vaccine causes similar side effects to the previously mentioned shots. It may also cause nausea and muscle pain throughout the body.

In the vaccine’s clinical trials, it was found that it may cause severe adverse reactions like blood clots and Guillain-Barré syndrome. These cases are rare but the FDA set restrictions on the use of the Johnson & Johnson vaccine to certain groups of individuals.

Novavax

Novavax is a double-dose vaccine available to all Americans aged 12 and older. There are no exceptions for younger children or babies. This vaccine currently doesn’t require a booster.

It also causes the same mild side effects as Pfizer-BioNTech and Moderna. These flu-like symptoms will usually resolve without medical treatment.

The Oxford-AstraZeneca vaccine is not currently available in the U.S.

Are There Ways to Prevent Side Effects from the COVID-19 Vaccine?

It can be difficult to completely prevent side effects from occurring because you don’t know how your body will react to the vaccine’s antigen.

It’s also likely that your body will have a physical reaction to the unknown antigen regardless of the preventative steps you take.

Should I take medication before going for my vaccination?

Taking medication before going for your COVID-19 vaccine shot to try and limit the symptoms is also not recommended by the CDC.

This is because there’s not enough evidence to tell doctors how medication can affect the vaccine’s effectiveness yet.

There are also concerns that pre-treating side effects can dampen your immune system’s response to the antigen in the vaccine, which could make it less effective.

For this reason, most healthcare providers will recommend steps you can take to ensure proper aftercare.

These steps can help you reduce side effects and alleviate any symptoms you may be experiencing.

What are the Rare Side Effects of the COVID-19 Vaccine?

Experiencing severe adverse effects after having received the vaccine — like a severe allergic reaction — is rare.

However, it is possible that this can happen. That’s why everyone who receives a COVID-19 vaccine is monitored by their vaccination provider for at least 15 minutes after they’ve been injected.

The following adverse reactions have been reported by the Center for Disease Control and Prevention (CDC) as rare side effects:

Anaphylaxis: A severe and potentially life-threatening type of allergic reaction that causes lightheadedness, breathing difficulties, wheezing, anxiety, and clammy skin. This reaction has been reported at a rate of five cases per million vaccine doses and usually develops quickly after administration. Anaphylactic shock requires immediate attention.

Thrombosis: A condition that causes blood clots to form and block blood vessels like veins and arteries. You may experience throbbing or cramping in one of your calves or thighs, swollen veins that are painful to touch, and red skin around the affected area. This reaction has a stronger link to the Johnson & Johnson vaccine compared to others and has been reported at a rate of four cases per million doses.

Guillain-Barré syndrome (GBS): A rare disorder that affects the immune system and causes damage to nerve cells. This can lead to muscle weakness and even paralysis. GBS may also have a stronger link to the Johnson & Johnson vaccine and has been reported at a rate of one to two cases per million doses.

Myocarditis and pericarditis: These are conditions that cause inflammation of the heart’s muscle and outer lining that can reduce its ability to pump blood. It may cause similar symptoms to a heart attack and requires immediate medical attention. This reaction is reported at a rate of around 70 cases per million doses of the vaccine.

If you experience any of the above conditions or suspect that you might have symptoms that indicate them, seek urgent attention from a healthcare provider.

Are There Any Long-Term Side Effects of the Vaccine?

The long-term effects of the COVID-19 vaccine are still unknown but current research suggests that it won’t cause any harm.

However, if you experience any severe adverse reactions like the ones discussed in the previous section, you may be at risk for longer-term issues.

These may include:

• Mental health issues like anxiety or depression 

• Post-traumatic stress disorder (PTSD) 

• Persistent leg pain 

• Hyperpigmentation caused by blood clots 

• Difficulty walking without assistance 

• Muscle weakness or numbness 

• Fatigue 

• Persistent heart conditions

If you’ve received a COVID-19 vaccination and experienced side effects for more than two months, you should speak to a healthcare provider.

Do the COVID-19 Booster Shots Cause Any Side Effects?

Side effects after having received your second dose and booster shots of the COVID-19 vaccine are usually similar to the ones experienced after the initial injection.

Most side effects are also mild to moderate and tend to resolve on their own in a couple of days.

However, some people have reported that they experience flu-like symptoms and pain more frequently compared to their first shot.

Scientists suspect that this is because the second vaccine dose and booster shots trigger a more intense immune response.

This is normally a good thing because it indicates that your body is training to fight against infection.

Getting Vaccinated After COVID-19 Infection

It’s recommended to get vaccinated even if you have had a COVID-19 infection. This is because the vaccine can boost your immunity and provide additional protection against new variants of the virus. You should wait until you have recovered from the acute illness (if you had symptoms) and have met the criteria to discontinue isolation. 

The CDC recommends waiting at least three months after a COVID-19 infection before getting vaccinated.

Steps to alleviate symptoms after vaccination

To alleviate mild side effects, you can try the following:

• Apply a clean, cool, wet washcloth over the injection site to reduce swelling and pain

• Use or exercise your arm to help reduce discomfort

• Drink plenty of fluids

• Dress lightly to manage any fever

• Consider over-the-counter pain relievers like acetaminophen or ibuprofen, but only if you don't have any contraindications

When to Speak to a Healthcare Provider

The COVID-19 vaccine may cause mild side effects that can be treated with over-the-counter medications.

However, it’s always better to speak to a doctor if you’re worried about any symptoms you experience.

You should make an appointment to see your healthcare provider if you’re unsure about the symptoms you’re experiencing.

You can also contact a doctor if you’d like more information about the side effects of the COVID-19 vaccine.

A good rule of thumb is to contact a doctor if any of the following happens:

• You experience severe pain or discomfort around the injection site

• Your side effects don’t resolve after a few days

• You’re worried about symptoms like dizziness, fainting, or breathing difficulties

• Your pain or discomfort starts interfering with daily activities

• You experience persistent fever, headaches, or lethargy

• You suspect that you may have an allergic reaction to the vaccine

If you are experiencing some of the symptoms we’ve covered or are worried about any other side effects, do not hesitate to seek medical advice from LifeMD.

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