The flu is a disease caused by influenza viruses. The flu can cause serious complications, which can lead to hospitalization and, in some cases, death.

However, the flu vaccine can lower your risk of getting the flu. It also reduces the severity of flu symptoms, even if you do get sick. The vaccine prevents you from transmitting the virus to others as well.

But like other vaccines, the flu shot can cause some side effects. They’re usually minor and go away after a few days.

The known side effects are muscle aches, swelling, and headache. Joint pain is not common, though some people report joint discomfort after getting the vaccine.

Read on to learn more about the link between flu shots and joint pain, including symptoms related to rheumatoid arthritis (RA).

The flu shot isn’t usually associated with joint pain.

Instead, it typically affects the muscle. This includes side effects like muscle soreness and swelling.

Muscle pain and swelling are signs your immune system is responding to the flu vaccine. It’s creating antibodies to protect you from an influenza infection.

Also, a flu vaccine involves an injection in your arm. This causes inflammation in the muscle, making your arm feel achy and swollen.

For some people, the muscle soreness can also cause joint pain and discomfort.

Additionally, according to a 2015 research article, there have been several reports of people developing arthritis after receiving the flu vaccine. These cases are rare.

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic joint inflammation.

An autoimmune disease occurs when the immune system attacks your body’s own tissue, causing inflammation. In RA, this involves the joints.

Over time, the inflammation causes chronic joint pain and damage. It can also affect other tissues and organs, such as the lungs.

Some people with autoimmune conditions, including RA, are concerned about getting vaccines. That’s because vaccines, like the flu shot, stimulate the immune system.

But there’s no evidence that the flu vaccine can trigger RA flare-ups. In fact, a 2019 study involving nearly 15,000 people found there’s no link between the flu vaccine and joint paint or RA flares.

Thus, researchers concluded the flu vaccine is safe for people with RA.

The flu itself can cause an RA flare. That’s because infections are an RA trigger.

When you have an infection like the flu, your immune system tries to fight it off. In RA, this can lead to increased inflammation.

The spike in inflammation can lead to a flare-up, causing worse joint pain and RA symptoms.

What’s more, the flu can also lead to other complications and infections, such as pneumonia. This can further exacerbate RA symptoms and flares.

RA itself can increase your risk of the flu and its complications. RA compromises your immune system, making it difficult to fight off infections.

However, RA medications can increase your risk as well. Drugs that suppress the immune system, also known as immunosuppressants, are commonly used to treat RA.

There’s concern these drugs reduce the effectiveness of the flu shot, which stimulates your immune system.

But according to a large 2020 study involving more than 30,700 people, the flu vaccine can still provide protection, even if you’re taking RA medication. Researchers found that the vaccine reduces the risk of flu and its complications, including pneumonia.

A 2021 research review also found the vaccine can lower the risk of hospitalization and death of flu complications.

Still, there are some other factors to consider. Whether you should get the vaccine depends on your medical history and what medications you’re taking.

But in general, it’s recommended for people with RA to get the flu vaccine. Talk with a doctor if you have concerns.

The known side effects of the flu vaccine include:

Typically, these side effects are mild and go away after a few days.

In most cases, the flu vaccine causes minor side effects like muscle aches, soreness, and swelling. It typically doesn’t cause joint pain.

That said, there’s no evidence the flu vaccine will cause RA flare-ups or joint pain. The flu itself, however, is known to trigger RA flares.

If you have RA, experts recommend you get the flu vaccine. RA increases your risk of the flu and its complications. But the vaccine can offer some protection, even if you’re taking immunosuppressants.