How Enbrel Works

In some people with arthritis, a signalling protein (cytokine) called Tumour Necrosis Factor (TNF) is present in the blood and joints in excessive amounts where it increases inflammation (pain and swelling).

Enbrel (etanercept) is another type of protein called a fusion protein that was developed by scientists to block TNF. It is built out of other proteins that are found in the human body including part of an antibody that can normally found in the blood, and a receptor called TNF receptor 2 that binds to TNF.

When Enbrel binds to TNF, it blocks it from working. This makes it part of a family of arthritis medicines called TNF Blockers. In blocking TNF, Enbrel suppresses the body’s 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.

In patients with arthritis, this medicine can:

  • Reduce the pain and swelling (inflammation) in arthritic joints
  • Improve day to day function
  • Prevent long-term damage caused by joint inflammation

Side Effects of Enbrel

Patients should talk to their doctor if they are concerned about any side effects.

All fevers and infections should be reported to a doctor.

MORE COMMON side-effects include:

  • Mild skin reaction at the injection site (itchiness, redness, and mild swelling)
  • Headaches
  • Upper respiratory tract infections (such as sinusitis)

RARE side-effects include:

  • Blood Counts – Enbrel can cause a drop in the numbers of white blood cells (which are needed to fight infection) or red blood cells (which carry oxygen). This is very rare and it is unusual for this to be a serious problem. Patients should get occasional blood tests so their doctor can monitor their liver and blood counts.
  • Infection – There is an increased risk of serious infection. Any infections or fevers should be taken seriously and reviewed by a doctor
  • Nervous System – There have been rare reports of some patients developing disorders that affect the nervous system (multiple sclerosis, seizures, or inflammation of the nerves of the eye) while taking Enbrel. Fortunately, these reports are exceedingly rare.
  • Heart – Patients should inform their doctor if they have congestive heart failure as Enbrel may make it worse.
  • Malignancy – When used for long periods of time, Enbrel may be associated with a small increased risk of lymphoma (cancer)

How to minimize the side-effects of Enbrel:

  • Enbrel should be taken as prescribed by a doctor

Enbrel should not be taken with other medications that also block TNF.

Who Should NOT Take Enbrel

Patients who should NOT be taking Enbrel (etanercept) include:

  • Patients who have had a previous serious allergic reaction to Enbrel (etanercept)
  • Patients taking another medication that also blocks TNF
  • Possibly patients who have cancer or have had a past history of certain cancers
  • Patients who have severe or uncontrolled congestive heart failure
  • Patients who have multiple sclerosis
  • Patients with active infections (such as tuberculosis)

Anyone who becomes pregnant while taking Enbrel should notify their doctor.

When to Call a Doctor

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

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

  • Fever, infection, or suspected infection
  • If another doctor has prescribed antibiotics to fight an infection
  • Upcoming surgery
  • Pregnancy
  • Planning to get a vaccination – not all vaccinations are safe with Enbrel
  • Development of a rash

Enbrel Video

Watch Dr. Andy Thompson, a Canadian rheumatologist, introduce Enbrel.