Cosentyx is a medication used to treat plaque psoriasis, an autoimmune skin condition that causes red, scaly patches on the skin. According to the sources provided, skin irritation is one of the possible side effects of Cosentyx. However, there is no specific information on how long this side effect may last.

The duration of skin irritation caused by Cosentyx may vary depending on individual factors such as the severity of the psoriasis, the dosage of the medication, and the patient's overall health. It is important to note that not all patients who take Cosentyx will experience skin irritation, and those who do may not experience it for the same length of time.

If you experience skin irritation while taking Cosentyx, it is recommended to speak with your healthcare provider. They may be able to adjust your dosage or provide additional treatment to help alleviate the symptoms. It is important to follow your healthcare provider's instructions and not to stop taking Cosentyx without consulting them first.

In conclusion, while skin irritation is a possible side effect of Cosentyx, there is no specific information on how long it may last. The duration may vary depending on individual factors, and it is recommended to speak with a healthcare provider if you experience this side effect.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/COSENTYX
[2] https://www.medicalnewstoday.com/articles/drugs-cosentyx-side-effects
[3] https://www.cosentyx.com/plaque-psoriasis/how-cosentyx-works