Cosentyx is a biologic drug that is used to treat autoimmune diseases such as psoriasis and psoriatic arthritis. According to the sources provided, there is no specific recommendation for how often Cosentyx levels should be monitored.

The first source [1] provides information about the patent for Cosentyx, but does not mention anything about monitoring levels of the drug.

The second source [2] is a research article that discusses the use of biologic drugs in the treatment of psoriasis. While the article mentions the importance of monitoring drug levels for some biologics, it does not specifically address Cosentyx.

The third source [3] is the FDA label for Cosentyx. The label provides information about dosing and administration of the drug, but does not include any specific recommendations for monitoring drug levels.

Overall, it appears that there is no consensus on how often Cosentyx levels should be monitored. It is important for patients to follow their healthcare provider's instructions regarding the use and monitoring of the drug. If patients have any questions or concerns about their treatment plan, they should discuss them with their healthcare provider.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/COSENTYX
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2945861/
[3] https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/125504s001s002lbl.pdf