When to see your doctor, if your post-flu shot shoulder pain doesn't let up.

By Leah Groth
November 08, 2019

Right out of the gate, it needs to be said that getting the flu shot is never a bad idea. Versions of the vaccine have been around for more than 70 years, according to the Centers for Disease Control and Prevention—and this year alone, flu vaccine manufacturers expect to supply up to 169 million doses of the vaccine.

Basically, the flu shot is safe, reliable, and its benefits greatly outweigh any small risks that may be associated with the vaccine. So, as long as you’re over six months of age, get it.

That said, it’s important to at least be aware of the risks that can accompany the flu vaccine. Typically, those are just temporary and include pain, swelling, and redness around the site of the injection—much like any shot—which may appear 24 to 48 hours after the actual shot.

But—and remember this is rare—if a flu shot isn’t properly administered, it can result in an uncommon, underdiagnosed type of shoulder injury commonly referred to as Shoulder Injury Related to Vaccine Administration, or SIRVA. Here, experts explain what SIRVA is, how it feels, and what you (and your doctor) can do to prevent it.

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What exactly is SIRVA

Ken Donohue, MD, a Yale Medicine orthopedic surgeon and shoulder specialist, explains to Health that SIRVA is an extremely rare condition in which pain and loss of function in the shoulder occurs following a vaccination—usually within 48 hours of administration of an injection in people who had no shoulder issues prior to injection. It can result in shoulder pain, weakness, stiffness or nerve inflammation (brachial neuritis). In very rare cases, it can result in nerve injury.

Just how uncommon is it? “I have seen very few cases of this in my patients as an orthopedic shoulder specialist,” Dr. Donohue maintains. And because it is so rare, there is little information available about it.

According to a 2012 case report published in the Journal of the American Board of Family Medicine, “the concept that adverse reactions, specifically those involving the shoulder, are very rare.” At the time of the report, researchers noted that only “a single” article on the concept existed. Seven years later, research is still incredibly limited.

While any sort of vaccination can lead to SIRVA, researchers found the majority were the result of the influenza vaccine. According to the report, nearly all who have reported such an injury, developed it within 24 hours.

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So, why does SIRVA happen?

Dr. Donohue explains that doctors and nurses are properly trained in “landmarking,” or determining where a vaccine should be given in the arm and using the proper needle length. “When a needle is injected too deep the deltoid muscle can be penetrated and structures within the shoulder can be damaged such as the rotator cuff or joint capsule,” he explains. In very rare cases the axillary or radial nerves in the upper arm could be injured.

According to the 2012 case report, “SIRVA is due to an inflammatory effect from vaccine administration into the subdeltoid bursa,” or a fluid-filled sac located under the deltoid muscle in the shoulder joint.

A 2018 study published in the Canadian Pharmacists Journal, specified that it “occurs when an injection is administered too high in the arm, and the vaccine is delivered to the shoulder capsule instead of the deltoid muscle.”

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What are the symptoms of SIRVA—and how is it treated?

While dull muscle ache pain after a vaccine injection is common, it usually disappears on its own with days. With SIRVA, on the other hand, an individual will usually start feeling pain within 48 hours of the vaccination, and doesn’t improve.

"In patients who experience SIRVA, months may pass by, and patients will still complain of increasing pain, weakness, and impaired mobility in the injected arm. Simple actions like lifting your arm to brush your teeth can cause pain," said Kelly Grindrod, a professor in the School of Pharmacy at Waterloo and one of the authors of the 2018 study.

People experiencing these symptoms should talk to their doctor. "It's important that we learn to recognize these signs of SIRVA so that we can access appropriate treatment," Grindrod points out.

In order to diagnose SIRVA, an ultrasound scan is needed, which can also determine the level and type of damage. Inflammation reducing oral medications and corticosteroid injections to the shoulder are common treatments for SIRVA, and additionally, physiotherapy may be recommended.

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Can SIRVA be prevented?

Most importantly, health care providers who administer vaccinations need to use proper vaccination landmarking techniques, according to Grindrod. However, if you are the one getting vaccinated, there are a few precautions you can take.

“It’s important to let the people administrating vaccinations see the entire shoulder, so that they can reference the necessary landmarks for proper injection,” says Dr. Donohue. “Wear a sleeveless shirt or shirt that can be removed in order to reveal the entire shoulder. Rolling up the sleeve may prevent the person administering the vaccine from seeing all of the landmarks necessary to administer appropriately.”

But again, just for good measure, keep mind that SIRVA is extremely rare, and is certainly not a reason to avoid getting the flu shot. “I can’t emphasize enough that the risks associated with not being vaccinated far outweigh the possibility of SIRVA,” says Dr. Donohue. “My advice is to still be vaccinated as you normally would but to talk to your primary care doctor about any concerns you may have.”

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