Cosentyx is a biologic drug that is used to treat psoriasis, psoriatic arthritis, and ankylosing spondylitis. While it is generally safe, some people may experience an allergic reaction to the medication.

According to the official Cosentyx website [2], signs of an allergic reaction to Cosentyx may include hives, itching, swelling of the face, lips, tongue, or throat, difficulty breathing, chest tightness, or skin rash. If any of these symptoms occur, it is important to seek medical attention immediately.

In addition to allergic reactions, there are other potential side effects of Cosentyx. These may include infections, such as upper respiratory tract infections or urinary tract infections, as well as diarrhea, nausea, and other gastrointestinal issues [3]. Patients may also experience headaches, fatigue, or injection site reactions, such as redness or pain at the site of injection [2].

It is important to note that these side effects may vary depending on the individual, and not everyone will experience them. Patients should discuss any concerns they have about side effects with their healthcare provider, and report any unusual symptoms that may arise during treatment with Cosentyx.

Sources:
[2] https://www.cosentyx.com/safety-and-side-effects
[3] https://www.healthline.com/health/drugs/cosentyx-side-effects