This article was reviewed medically by Jason R. McKnight. Dr. Judith M. Sullivan, MS, is a family medicine physician and clinical assistant professor. Texas A&M College of Medicine.
You may have some pain at the injection site after a flu shot.
- Side effects of the flu shot include headaches, fever, muscle soreness, and fever.
- Side effects of nasal spray include runny nose, wheezing, or sore throat.
- If you experience difficulty breathing following a flu shot, it is essential to seek medical attention.
Although side effects of the flu shot include soreness at the injection site, headaches, and other discomforts, these should not discourage you from getting vaccinated.
Rarely, the flu shot can cause an allergic reaction which a doctor must treat.
Here are the facts about side effects and how to distinguish between an allergic reaction and a normal response to the flu shot.
Side effects of the common flu shot
Side effects of the flu shot are not typical for everyone. The flu vaccine can cause side effects that are common and often include:
- Swelling or soreness at the injection site
There may be some soreness, swelling, or redness at the flu shot site. You can avoid soreness in your arms by taking ibuprofen (Advil) two hours before you get your flu shot.
- Mild fever
Your flu shot may cause mild fever (less than 101degF). It would help if you took ibuprofen (Tylenol) or acetaminophen (Tylenol) to manage the symptoms.
- Muscle pain
Feeling soreness in your arm after getting your flu shot is normal. Feeling muscle pains throughout your body the day after getting your flu shot is typical.
- Headache
You should not be alarmed by the possibility of experiencing headaches.
“Headache and fever are not signs of allergic reactions,” states Michael McNeil, Team Lead for Vaccine Safety Datalink, CDC’s Immunization Safety Office. These reactions may occur when the patient’s immune response to a vaccine is impaired.
Important: Although some believe you can get influenza from the flu shot, it isn’t true since the flu vaccine doesn’t contain active virus particles.
- Nausea
As your immune system reacts to the vaccine, it is common to feel nausea, stomach pain, and general sickness.
These side effects usually appear within a few hours of injection. They should last for a few days, according to the CDC.
What side effects can the flu vaccine nasal spray cause?
A nasal spray flu vaccine can help avoid side effects like arm soreness. However, it also comes with its fair share of side effects.
Side effects of the nasal spray vaccine are:
- Runny nose
- You are gasping
- Sore throat
- Headaches
- Fever
- Nausea
The CDC states that nasal vaccines are safe for most people between 2 and 49 years old. Some groups should not receive the nasal spray:
- People with a weak immune system
- Adults over 50 years old
- Children aged 2-4 with severe Asthma have been in the hospital for over a year.
- Children ages 2-17 who are taking medications such as aspirin and salicylate-containing therapies
- Women who are pregnant
It would help if you were also cautious when receiving the nasal spray vaccine.
- People living with Asthma over the age of 5
- Lung disease, heart disease, and diabetes are all possible.
- Acutely ill people
Quick tip See a complete list of those who should not use the nasal spray and those who should be cautious on the CDC website.
How to consult a doctor regarding side effects of flu shots
Although the above side effects are common reactions to flu vaccines, monitoring your response to the vaccine is essential to ensure you do not have an allergic response.
Although allergic reactions are uncommon, they can still be severe. They occur in approximately 1.3 out of every 1,000,000 vaccines.
A serious allergic reaction to flu vaccines can cause severe reactions such as:
- Trouble breathing
- Wheezing or hoarseness
- Pallor/paleness
- Weakness
- Fast heartbeat
- Dizziness
McNeil says these symptoms often occur within a few minutes or hours of receiving the shot. They require immediate medical treatment.
Like all vaccines, the flu shot contains components that could cause allergic reactions. Most allergic reactions to vaccine components are due to an allergy to egg protein, gelatin, or other additives. Although the flu shot contains trace amounts of eggs, most people with mild egg allergies can still receive vaccines.
Severe non-allergic reactions
The influenza vaccine can cause paralysis in sporadic cases.
It is believed that one to two people will develop GBS from every one million people who have been vaccinated. GBS can happen within days or weeks of vaccination. It is characterized by muscle weakness, difficulty controlling the eye muscles, or difficulty swallowing.
These symptoms should be reported to your doctor.
Insider’s Takeaway
The flu vaccine’s side effects, whether a nasal spray or shot, can include nausea, fever, headaches, and nausea. It is essential to be vaccinated every year.
McNeil says flu vaccines have a strong safety record. “Hundreds of millions have received flu vaccines safely over the last 50 years. There has also been extensive research to support the safety of flu vaccines.”
Influenza can be dangerous, especially for children, older adults, and people with compromised immune systems.
A flu shot can reduce the chance that you will contract the disease or pass it on to others. Although there may be side effects, these are usually minor and temporary and shouldn’t affect your decision to get the flu shot.