What side effects does secukinumab commonly cause?
Secukinumab (Cosentyx) can cause several side effects, most of which are mild to moderate. Commonly reported effects include upper respiratory infections, headache, and reactions at the injection site (such as redness or pain) [1]. Some patients also report diarrhea and nausea [1].
Can secukinumab cause weight gain?
Weight gain is not a well-known or commonly listed direct side effect of secukinumab in typical prescribing information summaries. When people notice weight changes after starting biologics, the cause is often indirect (for example, changes in inflammation level, diet/appetite, activity level, or other medications used alongside treatment), rather than a consistent drug-driven effect.
If you’re seeing weight gain after starting secukinumab, it’s worth discussing with the prescribing clinician to check for other explanations, such as:
- steroid use (for example, prednisone tapers or dose changes)
- thyroid problems
- fluid retention from another condition
- other medications started around the same time
What side effects might look like “water weight”?
Secukinumab can affect infection risk, and infections can sometimes lead to temporary changes in weight related to illness, appetite, or fluid balance. If weight gain is accompanied by swelling (face/legs), shortness of breath, or rapid changes over days, those symptoms need prompt medical evaluation to rule out fluid-related causes or serious complications.
What serious side effects should people watch for?
Patients should seek urgent care if they develop signs of a serious allergic reaction (such as trouble breathing, swelling of the face/throat, or widespread hives) [1]. People should also contact their clinician right away for symptoms of an infection (fever, worsening cough, or painful/red skin) because biologic therapies can increase susceptibility to infections [1].
When should you call your doctor about weight changes on secukinumab?
Call your clinician if weight gain is:
- rapid (for example, several pounds in a few days)
- paired with swelling, shortness of breath, chest pain, or new severe fatigue
- persistent and unexplained over weeks
- occurring alongside new steroid use or dose changes
Your clinician may review your full medication list and underlying conditions, and check for common contributors (like thyroid function or fluid retention).
Are there alternatives if weight gain is a concern?
If weight gain is a key issue, the most practical next step is usually to review:
- whether you’re also using corticosteroids
- whether your symptoms improved (and activity level changed)
- alternative psoriasis/psoriatic arthritis biologics or other treatments that may fit your situation
A switch should be individualized, since weight changes can have many causes unrelated to secukinumab itself.
Sources:
1. Drugs.com. “Cosentyx (secukinumab) Side Effects.” https://www.drugs.com/sfx/cosentyx-side-effects.html