Key takeaways

  • Studies show that Cosentyx is a safe and effective medication that doesn’t directly cause brain or nerve problems. While some older medications had warnings about nerve issues, Cosentyx is a different type of drug that doesn’t usually carry those same risks.
  • Since its release, there have been rare reports of possible neurological issues, such as a loss of smell and movement difficulties. There are also extremely rare cases of severe brain infections or nerve conditions like Guillain-Barré Syndrome.
  • Cosentyx works by blocking a specific protein (IL-17A) to stop the inflammation that causes skin and joint pain. However, it also weakens your immune system, which, in very rare cases, can allow an infection to reach your brain or spinal cord.

Cosentyx is a brand-name prescription medication used to treat various conditions, including psoriatic arthritis and plaque psoriasis.

Like all medications, Cosentyx can cause side effects for some people. The most common are diarrhea, cold symptoms, and upper respiratory tract infections. However, this article focuses on rare neurological side effects reported by people taking Cosentyx.

Some older psoriasis medications, such as TNF-alpha inhibitors, carry warnings for serious neurological complications. However, clinical trials of Cosentyx, an IL-17A inhibitor, did not reveal any neurological complications.

This article discusses some of the rare neurological side effects associated with Cosentyx, how they might happen, and signs that you may want to discuss with a doctor.

Before Cosentyx was launched, clinical trials didn’t show that it caused neurological side effects. However, the following neurological side effects have been reported since it became available:

Headaches

Headaches are a common side effect of IL-17 inhibitors like Cosentyx. In most cases, headaches are temporary, easy to manage, and not a sign of a dangerous neurological condition.

Anosmia (loss of smell)

Losing your sense of smell may be a rare side effect of Cosentyx, although more research is necessary to explore the link.

A 2023 review of the FDA’s adverse event database identified the loss of smell as a potential toxicity signal associated with Cosentyx. Anosmia can indicate damage to the nervous system, but it can also be caused by nasal congestion or sinus infections.

Movement difficulties

A 2024 assessment of the safety profile of secukinumab using the FDA’s postmarketing databases highlighted very rare reports of movement-related issues. These include hypokinesia (decreased bodily movement) and dysstasia (difficulty standing).

Guillain-Barré Syndrome (GBS)

GBS is a rare condition in which the immune system attacks peripheral nerves, leading to muscle weakness and, in some cases, paralysis.

A 2024 case study described a person developing GBS after starting Cosentyx. Research is necessary to determine whether the use of Cosentyx and GBS is linked.

Severe brain infections

Cosentyx alters your immune system, increasing your overall risk of infections. In extremely rare cases, infections can spread to the brain.

A 2021 case study described a person who developed herpes simplex encephalitis (brain inflammation caused by the herpes virus) and multiple streptococcal brain abscesses after taking secukinumab for 10 months.

Cosentyx works by blocking the interleukin-17A (IL-17A) protein. This protein has a major role in causing the painful inflammation associated with psoriasis and arthritis. However, IL-17A also plays a critical role in your immune system’s ability to fight off bacterial and fungal infections.

When this protein is blocked, your body is less able to defend itself against certain pathogens. If an opportunistic virus or bacteria slips past your immune defenses, it may lead to secondary infections that invade the central nervous system.

It’s also possible that altering the delicate balance of cytokines, like IL-17A, in the immune system can trigger autoimmune nerve issues, such as GBS, in people who are genetically predisposed.

Before starting Cosentyx, your doctor will evaluate you for tuberculosis and ensure your vaccinations are up to date. They will also monitor your blood counts and liver function regularly to ensure your body is handling the medication well.

Because the medication lowers your immune defenses, you should avoid receiving live vaccines while taking it. To avoid picking up infections, practice good hand hygiene and avoid contact with people who are sick whenever possible.

You may not experience any side effects of Cosentyx, but it’s important to know when to seek medical advice.

Contact your doctor right away if you experience any of the following symptoms:

  • high fever or chills
  • muscle aches
  • severe headaches
  • confusion
  • a cough that won’t go away
  • worsening stomach pain
  • diarrhea
  • unexplained muscle weakness
  • tingling in your limbs
  • difficulty standing

You should seek emergency medical help if you show signs of a severe allergic reaction, such as

  • feeling faint
  • rash
  • trouble breathing
  • swelling of your face, lips, or throat

Serious neurological side effects from Cosentyx are extremely rare. However, it is fairly common to experience a headache.

Medical experts consider Cosentyx a safe and effective medication that doesn’t cause neurological complications.

If you experience unusual muscle weakness or other symptoms that bother you, call your doctor for advice.