Enbrel Side Effects & Safety

Based on experience from clinical studies and post-marketing safety reporting across all indications, the most common side effects associated with Enbrel treatment were infections and injection site reactions.

According to results from two placebo-controlled Phase 2 and 3 clinical trials and one active-control Phase 3 trial, the most common side effects or adverse events included infections, injection site reactions, diarrhea, and rash.


Most common side effects in studies of Enbrel in RA

Placebo-controlled studies*

2-year, active-control study

Side effect Enbrel (all doses) (N=349) Placebo (N=152) Enbrel (all doses) N=4150 MTX (N=217)
Infections (total) 50% 39% 81% 86%
Upper respiratory infections 38% 30% 65% 70%
Non-upper respiratory infections 21% 15% 54% 59%
Injection site reactions 37% 11% 43% 18%
Diarrhea 8% 9% 16% 16%
Rash 3% 2% 13% 19%
Pruritis 2% 1% 5% 5%
Pyrexia 3% 0% 2% 4%
Urticaria 0% 1% 2% 4%
Hypersensitivity 0% 0% 1% 1%
*Includes data from 6 month study in which both arms received methotrexate (MTX).


Warnings and precautions with Enbrel

There are several warnings and precautions related to Enbrel that you should be aware of before starting treatment.

Serious infections. There is an increased risk for developing serious infections with Enbrel, including tuberculosis (TB), bacterial sepsis, invasive fungal infections (fungal infection inside the body) such as histoplasmosis, coccidioidomycosis, or blastomycosis (people who live in the Ohio or Mississippi River Valleys are at increased risk for these types of infections), and other opportunistic infections (infections that result from microorganisms that normally do not cause diseases in humans). The increased risk of infection with Enbrel occurs because the drug can decrease the ability of the immune system to fight infections. If you develop a serious infection while taking Enbrel, you should discontinue the treatment.1

Before starting treatment with Enbrel, you should be tested for latent TB, and, if positive, you should receive treatment for TB before starting Enbrel. All patients should be monitored for active TB during treatment with Enbrel.1

The signs of TB include a cough that persists, a low-grade fever, weight loss, and loss of body fat and muscle.

If you carry the hepatitis B virus (HBV), a virus that affects the liver, HBV may become active during treatment with Enbrel. Before you start treatment with Enbrel, as well as during treatment and for several months after you stop treatment, your doctor will give you a blood test to see if you have HBV infection. The signs of HBV infection include muscle aches, fatigue, yellow-looking skin or eyes, dark urine, clay-colored bowel movements, vomiting, fever, chills, stomach ache, skin rash, and loss of appetite. Tell your doctor if you have any of these symptoms.1
Cancer. Enbrel and other anti-TNF treatments have been shown to increase the risk of developing certain types of cancers. While this risk is small, it does exist. Cases of lymphoma have occurred in children and adolescents who received other anti-TNF treatments.1
Other health conditions. Enbrel can cause a worsening of congestive heart failure (signs include shortness of breath, swelling of feet or ankles, and sudden weight gain), demyelinating disease (such as MS), a Lupus-like autoimmune disorder, or cytopenia (a deficiency of cells that make up blood, with symptoms including bruising, bleeding, or persistent fever). If you experience any of these, contact your doctor immediately.1 Patients diagnosed with multiple sclerosis or other demyelinating disease should not use Enbrel.


Pregnancy and nursing

Enbrel is a pregnancy category B drug. Animal studies found no evidence that Enbrel poses harm to the fetus. However, there have been no well-controlled studies in pregnant women. Therefore, Enbrel should be used during pregnancy only if it is clearly needed.1

It is not known whether Enbrel is excreted into human milk. Because of the risk of adverse effects, women who are taking Enbrel should either not breastfeed their children or discontinue the drug.1


Drug interactions

Use of live vaccines should be avoided while taking Enbrel.1

Because of the increased risk for developing infections, you should not take Enbrel with other immune-modulating biologic treatments.1

Use of Enbrel at the same time as the anti-cancer drug cyclophosphamide is not recommended.1

Written by: Jonathan Simmons | Last reviewed: September 2013.
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