Do people on Cosentyx (secukinumab) get flu-like side effects like a vaccine?
Cosentyx is an immunomodulating medication used for autoimmune conditions such as plaque psoriasis, psoriatic arthritis, and ankylosing spondylitis. Flu shots work by stimulating an immune response against influenza, and their most common side effects are typically mild and short-lived (such as arm soreness or temporary flu-like symptoms).
Cosentyx does not cause the same typical “vaccine reaction” pattern. Instead, its side effects are driven by how it affects parts of the immune system (it blocks IL-17A). That can lead to different issues than those seen after a flu shot.
What side effects are more typical for Cosentyx?
A key known risk for Cosentyx is infection-related effects, including an increased chance of upper respiratory infections and other infections, because it changes immune signaling. Another commonly discussed issue with IL-17 blockade is fungal infections (especially candidiasis/“yeast” infections). These are not the usual side effects from a flu shot.
What side effects are more typical for a flu shot?
After a flu shot, many people have mild, temporary effects such as:
- sore or red/swollen arm at the injection site
- fatigue, headache, or low-grade fever
These generally resolve within a day or two, and they do not typically include problems like recurrent infections over time.
Can Cosentyx make you feel “flu-ish” after starting?
Some people report symptoms that can overlap with vaccine “flu-like” feelings (such as fatigue or feeling unwell), but Cosentyx is not expected to cause a classic, predictable short-lived vaccine reaction. If someone develops fever or feels very sick while on Cosentyx, clinicians usually treat that as a possible infection concern rather than a normal vaccine response.
Does this mean you should avoid getting a flu shot while on Cosentyx?
In many cases, people on biologics like Cosentyx can still get an inactivated (non-live) flu vaccine, and doing so may help reduce influenza risk. What matters is the specific vaccine type and your health status (for example, if you’re currently sick, or if you have other immune-related risks). Your prescribing clinician can advise what’s appropriate for your situation.
What should patients watch for that are different from flu shot reactions?
After a flu shot, side effects are usually mild and brief. With Cosentyx, side effects that warrant prompt medical advice are more likely to be infection-related, such as:
- fever or chills that don’t quickly resolve
- worsening sore throat, cough, or shortness of breath
- signs of fungal infection (for example, persistent mouth/genital yeast symptoms)
If you tell me what side effect you’re comparing (e.g., fever, fatigue, injection-site pain, sore throat), I can map it more directly to what’s expected from a flu shot versus what’s more typical for Cosentyx.