5 Medications That Interact With the Flu Shot

“When getting an injected steroid in a joint or epidural space, you get some systemic absorption of the medication, which causes a transient dampening of your immune system,” says William Raoofi, M.D., of the Center for Interventional Pain Medicine at Mercy Medical Center in Baltimore, Maryland, “Then when you are vaccinated and exposed to the weakened flu virus, your immune system is not as good at responding to it.”

When suppressed, your immune system does not effectively recognize the inactive flu virus introduced by the vaccine. Then your immune system could fail to launch a strong attack on the live virus if you are exposed later.

Raoofi adds that as you age, your body produces fewer and weaker immune cells that cannot remember the virus you were vaccinated against.  Steroids can further weaken your ability to launch a strong immune response to protect yourself if you are exposed to the flu later. 

When an older adult comes into his office for a steroid injection and has received or plans to receive the flu vaccine within the next two weeks, Raoofi says he reschedules the appointment for two weeks after the vaccine.

“It is a risk-benefit decision,” he says. Due to the high risk of death or complications for an older person with the flu, Raoofi says that it is important to leave a two-week window for the immune system to ramp up its response to the flu virus before receiving the steroid injection. 

2. Oral prednisone

Prednisone is a steroid that is taken orally to decrease inflammation, suppress an overactive immune system or replace cortisol. It treats conditions like asthma, arthritis and inflammatory bowel disease. Prednisone, combined with medications like cyclosporine, also suppresses the immune system after organ transplantation to prevent rejection.

At doses of 20 mg per day for two weeks or more, prednisone can decrease your body’s ability to form antibodies, weakening your immune response to the flu vaccine. “High doses of steroids can weaken your immune system and potentially reduce the effectiveness of the flu vaccine," Pepin says.

3. Non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen and aspirin

Over-the-counter pain relievers and fever reducers, taken before or after a flu vaccination, may also decrease your response to the vaccine. These medications include acetaminophen (Tylenol), aspirin and non-steroidal anti-inflammatory drugs (NSAIDS) like ibuprofen (Motrin, Advil) and naproxen (Aleve).

“When you get the flu vaccine, a lot of people will get a temperature of 99 degrees, malaise and pain at the injection site for up to 24 hours,” says Pepin. “This means your immune system is responding to the flu virus.”

According to Pepin, taking acetaminophen or ibuprofen to prevent or reduce your temperature can reduce your ability to ramp up your immune response.

If you are uncomfortable after the flu vaccine, Pepin recommends taking acetaminophen (Tylenol) which does not have an anti-inflammatory effect like NSAIDs and aspirin. However, she does not recommend taking acetaminophen until six hours after the vaccine to give your body time to start its immune response.

4. Chemotherapy and radiation therapy

The American Cancer Society confirms that chemotherapy and radiation therapy can diminish your response to the flu vaccine, and encourages consultation with your physician regarding the best time to be vaccinated.

Pepin says it’s important to understand that chemotherapy drugs break down your immune system by attacking not only cancer cells, but also healthy cells.

These healthy cells, often located in your bone marrow, produce  immune cells that support your immune system. The result is that you will not be able to generate as many immune cells to remember and fight the strain of flu you were vaccinated against.

5. Biologics

Biologics include medications that bind to certain proteins on immune cells to fight cancer cells or the inflammation that results when your own body attacks itself.

Medications like atezolizumab (Tecentria), avelumab (Bavencio), durvalumab (Imfinzi), ipilimumab (Yervoy), nivolumab (Opdivo) and pembrolizumab (Keytruda) fight cancer. They help the immune system find and destroy cancer cells and may also damage healthy cells.

Other biologics like etanercept (Enbral), adalimumab (Humira) and infliximab (Remicade) bind to proteins on immune cells to decrease the inflammatory response in autoimmune diseases like rheumatoid arthritis, psoriatic arthritis, psoriasis and inflammatory bowel disease.  

Pepin recommends consulting your physician to determine at what point in your therapy you should get the flu vaccine, keeping in mind that settling for limited protection may be better than delaying your vaccine.