Common Flu Shot Side Effects To Know

Being a little sore after your jab is a small price to pay to prevent influenza.

Flu vaccines, much like diverse solutions in life, lack a one-size-fits-all approach. Indeed, an array of influenza vaccines is available each year, tailored to varying needs. Administration can occur through injection or nasal spray, with specific dosages designed for both the youngest and oldest recipients. These vaccines can be developed using either an inactivated (non-viable) virus or an attenuated (weakened yet live) virus. The production method may or may not involve the use of eggs for virus cultivation.

Despite these nuanced differences, the underlying similarities among the various flu vaccine iterations remain significant. Given the mutability of the flu virus and the potential co-circulation of multiple strains, scientists work to forecast the most active strains for the upcoming flu season. Subsequently, the flu vaccine is formulated to provide protection against these anticipated strains.

However, while the vaccines offer comparable protection, their manufacturing processes and intended recipients differ. Consequently, the potential side effects of flu vaccinations might exhibit slight variations.

The selection of the appropriate vaccine hinges on factors such as age, health status, and allergies. Nonetheless, with minimal exceptions, it remains crucial for all individuals aged 6 months and older to undergo annual influenza vaccination.

Why Do Flu Vaccines Cause Side Effects?

Vaccines universally hold the potential to induce side effects, and the majority of these symptoms fall well within the realm of normalcy.

According to Michael Knight, MD, an assistant professor of medicine at George Washington University Medical Faculty Associates in Washington, DC, and a primary care physician, “Side effects essentially indicate the functioning of your immune system. They signify a rapid migration of immune cells to the site of vaccine injection to initiate a response.”

Interestingly, localized soreness at the injection site emerges as the prevailing side effect subsequent to any vaccine administration.

Flu vaccines, having been in existence since the 1930s, maintain an established track record of safety. The majority of flu vaccine side effects manifest as mild and transient, subsiding within a few days.

Peruse further to uncover potential post-flu shot experiences. (It’s important to emphasize that contracting the flu itself is an impossibility from the vaccine!) For a vast majority of individuals, these potential side effects, most of which are mild or infrequent, should not deter them from seeking protection against influenza.

Flu Shot Side Effects

The standard-dose flu vaccine, tailored for individuals aged 6 months to 64 years, comprises an inactivated (non-viable) influenza virus. Predominantly, the following side effects are associated with this vaccine:

1. Localized discomfort: Pain, swelling, or redness at the injection site.

2. Systemic symptoms: Headache or muscle aches, accompanied by potential nausea.

3. Fatigue: A sense of tiredness.

4. Mild fever: Slight elevation in body temperature.

William Schaffner, MD, a professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine, as well as the medical director of the National Foundation for Infectious Diseases, notes, “Nearly everyone experiences arm soreness. This usually subsides within a few hours, though some individuals might still have residual discomfort the following day. Moreover, around 3% of people might encounter fatigue, aches, pains, and headaches on the day after.”

It’s imperative to recognize that these side effects are characteristic of most injected vaccines, signifying the activation of your immune system. However, the absence of these effects doesn’t imply an ineffective immune response to the vaccine, as reactions exhibit variability among individuals.

Rare Flu Shot Side Effects

Thankfully, significant adverse effects resulting from the flu vaccine are exceedingly uncommon. A notable instance involves a minuscule elevated risk of Guillain-Barré Syndrome (GBS), a neurological disorder.

Guillain-Barré syndrome arises following just one or two instances out of every million vaccine doses administered, as reported by the Centers for Disease Control and Prevention (CDC). The connection between GBS and the flu vaccine is such that if an individual develops GBS within six weeks of receiving the vaccine, it’s advised not to pursue the vaccine again, according to Dr. Schaffner.

While some GBS cases might lead to enduring nerve damage, a majority of those affected eventually achieve full recovery. Intriguingly, research suggests that the likelihood of contracting GBS is actually higher after contracting the flu itself, as opposed to receiving the vaccine.

The occurrence of severe allergic reactions is exceedingly rare, impacting fewer than 1 or 2 individuals per million recipients. Signs of a severe reaction encompass:

1. Difficulty breathing

2. Hoarseness or wheezing

3. Swelling around the lips or eyes

4. Hives

5. Paleness

6. Weakness

7. Rapid heartbeat

8. Dizziness

These symptoms commonly manifest within hours following vaccine administration. If an individual experiences any of these symptoms, it is imperative to immediately contact a healthcare provider or dial 911 for prompt assistance.

Flu Shot Side Effects for People 65 and Older

Specially tailored vaccines are available for individuals aged 65 and above, recognizing their distinct needs. One of these vaccines maintains the identical antigen dosage (the viral component that prompts an immune reaction) as the version administered to younger adults. This vaccine, however, incorporates an adjuvant—an additive designed to stimulate a more potent immune response. The second vaccine, intended for this demographic, is a high-dose variant, containing fourfold the quantity of antigen.

Whichever of these vaccines is administered, the prevalent side effects remain consistent across all inactivated flu vaccines: localized discomfort at the injection site, possibly accompanied by minor muscle discomfort or a slight elevation in body temperature.

Dr. Schaffner underscores, “All injectable vaccines exhibit comparable side effects.” Similarly, the infrequent severe side effects are uniform across these vaccines as well.

Nasal Spray Flu Vaccine Side Effects

The nasal spray vaccine is an option designated for individuals aged 2 to 49 who aren’t pregnant and lack severe underlying health conditions. While predominantly utilized in pediatrics, certain adults choose this method to avoid needles, if feasible.

Unlike merely being an inhaled alternative to the injectable form, this vaccine incorporates a weakened—not deceased—iteration of the flu virus, strategically formulated to incite the immune system.

The absence of flu onset post-vaccination stems from the virus’s careful engineering, ensuring it fails to replicate when subjected to slightly higher internal body temperatures.

Frequently encountered effects linked to this vaccine encompass:

1. Cough

2. Headache

3. Runny nose

In the pediatric demographic, additional symptoms like wheezing, vomiting, muscle discomfort, sore throat, and mild fever might manifest.

The CDC emphasizes that in the event of such occurrences, they typically emerge shortly after vaccination and exhibit mild, transient nature.

An Egg-free Vaccine Option

The majority of influenza vaccines are produced using eggs as a medium for cultivating the vaccine cells. Understandably, individuals with egg allergies have harbored concerns about receiving such vaccines. Nevertheless, it’s worth noting that for most people with egg allergies, the flu vaccine poses no significant issues.

In line with this, the CDC proposes that individuals who have experienced severe allergic reactions to eggs in the past should undergo their flu vaccinations under the observation of a healthcare professional capable of identifying and addressing severe allergic responses.

For those who have encountered severe allergic reactions, including anaphylaxis, following egg-based flu vaccines, it’s advisable to avoid future egg-based flu vaccinations. Fortunately, they may still be eligible for one of the alternative flu vaccines not reliant on eggs. However, their vaccine administration should occur under the vigilant supervision of a healthcare provider equipped to discern and manage intense allergic reactions.

Determining the most suitable among the available flu vaccines requires a consultation with a healthcare provider.

A Quick Review

Receiving a flu shot can sometimes entail enduring a mildly sore arm for a brief period. Additionally, certain individuals might encounter side effects such as headaches, nausea, or a mild fever. However, it’s crucial to highlight that severe side effects are infrequent.

In the vast majority of cases, the side effects arising from a flu shot are both mild and transitory. Given this, the question arises: why take the chance of contracting the flu, a condition that can potentially result in significant complications? Opting for a flu shot proves notably safer than running the risk of contracting the flu itself.