Cosentyx is a medication that is used to treat various inflammatory conditions such as psoriasis, psoriatic arthritis, and ankylosing spondylitis. While it is an effective medication, it can also have side effects. According to the sources provided, the common Cosentyx side effects are as follows:

1. Upper respiratory infections: This is the most common side effect of Cosentyx. It can cause symptoms such as a runny nose, sore throat, and cough. [1][2]

2. Diarrhea: Cosentyx can cause diarrhea, which may be mild or severe. If diarrhea persists, it is important to contact a healthcare provider. [2][3]

3. Headaches: Cosentyx can cause headaches, which may be mild or severe. If headaches persist, it is important to contact a healthcare provider. [1][3]

4. Injection site reactions: Cosentyx is given as an injection, and it can cause reactions at the injection site such as redness, swelling, and pain. [1][2]

5. Nausea: Cosentyx can cause nausea, which may be mild or severe. If nausea persists, it is important to contact a healthcare provider. [3]

6. Fatigue: Cosentyx can cause fatigue, which may be mild or severe. If fatigue persists, it is important to contact a healthcare provider. [1][2]

7. Back pain: Cosentyx can cause back pain, which may be mild or severe. If back pain persists, it is important to contact a healthcare provider. [3]

It is important to note that not everyone who takes Cosentyx will experience these side effects. However, if any of these side effects persist or worsen, it is important to contact a healthcare provider. Additionally, there may be other side effects associated with Cosentyx that are not listed here. Patients should consult with their healthcare provider for more information on the potential side effects of Cosentyx.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/COSENTYX
[2] https://www.cosentyx.com/safety-and-side-effects
[3] https://www.healthline.com/health/drugs/cosentyx-side-effects