How Stelara Works

Stelara works by blocking interleukin-12 (IL-12) and interleukin-23 (IL-23). IL-12 and IL-23 are two signalling proteins, or cytokines, that regulate the immune system and are related to the body’s inflammatory response.

Stelara is itself a type of protein known as a monoclonal antibody. It binds to both IL-12 and IL-23, and in doing so, prevents them from binding to their receptors. Immune system cells like T-cells, a type of white blood cell, rely on signals like IL-12 and IL-23 to become activated or “switched on”.

When IL-12 and IL-23 are tied up by Stelara, the messages that would normally fire up T-cells don’t get through as often, and the overall effect is suppression of the immune system. Though this suppression can make it slightly harder for patients to fight off infections, it also helps to stabilize an overactive immune system and treat the symptoms of arthritis and psoriasis.

Side Effects of Stelara

The most common side effects of Stelara are upper respiratory tract infections (nasopharyngitis) and headache.

Other possible side effects include:

  • Injection site reaction – Stelara can rarely cause a reaction (redness, pain, & itching) at the injection site. Patients should tell their doctor if these are severe.
  • Rare brain problems – Some patients have very rarely developed a rare brain problem called Reversible Posterior Leukoencephalopathy Syndrome (RPLS) while taking Stelara. This is very rare and potentially reversible. Stelara should be stopped if this occurs.
  • Cancer – Ustekinumab has very rarely been associated with developing cancer. Patients should tell their doctor if they have had cancer in the past or have a family history of cancer.

Who Should NOT Take Stelara

People that should NOT take Stelara include:

  • Those with a fever or possible infection
  • Pregnant or breastfeeding women
  • Anyone who has had an allergic reaction to Stelara
  • People who have had a rare brain problem called RPLS
  • Possibly patients with a history of certain types of cancers

Patients who are about to have surgery should discuss stopping Stelara with their doctor. The medication can be restarted once things have healed and there are no signs of infection.

When to Call a Doctor

People taking Stelara should call a doctor if they feel sick and want to stop, or if they are concerned about any side effects.

Other reasons for people taking Stelara to call a doctor include:

  • Fever or possible infection
  • Upcoming surgery
  • Becoming pregnant or planning on pregnancy
  • Planning any vaccinations
  • Headache, confusion, seizures, or vision trouble