Cosentyx (secukinumab) isn’t a vaccine, so it doesn’t cause “flu shot” reactions on purpose. It’s a therapeutic antibody that can affect your immune system, so it has its own set of possible side effects. Some people report feelings that might resemble flu-like symptoms, but that’s not the typical or intended reaction like a flu shot. Here’s what’s commonly seen and what to watch for:
Common, more likely side effects
- Injection-site reactions: redness, itching, pain, or swelling where the shot was given.
- Infections: especially upper respiratory infections (cold symptoms, sore throat, nasal congestion).
- Headache, fatigue, nausea, diarrhea, or cough.
Less common but important
- Fever or malaise can occur, but this usually signals an infection rather than a vaccine-like reaction.
- Yeast infections (mucosal candidiasis) because IL-17A helps protect mucosal surfaces.
- Serious infections (pneumonia, cellulitis, sepsis) are rare but require urgent medical attention.
- Allergic reactions or hypersensitivity (rash, swelling, trouble breathing) — seek emergency care if these occur.
- Rare effects: new or worsening inflammatory bowel disease symptoms, neutropenia, or other immune-related effects.
Vaccination considerations
- Inactivated flu vaccine is generally considered safe for people on Cosentyx, but you should discuss timing with your prescriber.
- Live vaccines (for example, some nasal flu vaccines) are usually avoided while on Cosentyx.
- Vaccines may work less effectively while on immunomodulatory therapy; your doctor can advise on the best approach for you.
If you’re worried about flu-like symptoms after starting Cosentyx
- Monitor for fever, body aches, or fatigue—especially if you also have signs of infection (sore throat, cough with fever, shortness of breath, chest pain).
- Contact your healthcare provider if you develop a fever ≥100.4°F (38°C) or if you have any severe or persistent symptoms, signs of infection, or an allergic reaction.
- Keep a log of any side effects you notice after injections to share with your doctor.
If you’d like, tell me:
- What condition you’re using Cosentyx for,
- Any other meds you’re taking,
- Any symptoms you’ve noticed after injections.
I can tailor the information to your situation and help you decide what to discuss with your clinician. And remember, this isn’t medical advice—please consult your healthcare provider for medical guidance specific to you.