What Are the Most Common Infliximab Side Effects?

Infliximab, also known by the brand name Remicade®, can cause a number of different side effects. Common adverse reactions can include headache, nausea, diarrhea, abdominal pain, and localized skin redness and swelling. Patients taking the drug can have a reactivation of infections that had been lying dormant in the body, such as tuberculosis or hepatitis. They are also at risk for infection with other viruses, bacteria, or fungi obtained from the environment. Rarer infliximab side effects can include decreases in patients' blood counts and the development of different cancers.

Many people experience certain infliximab side effects immediately after receiving the medication. These symptoms are typically mild. They can include headache, nausea, diarrhea, abdominal pain, cough, and joint pain. Some patients have localized redness or swelling at the site of infusion. Often these symptoms improve with time, and are not a reason to stop treatment with the medication.

More serious infliximab side effects can include reactivation of latent diseases already present in the patients. This can happen because the medication suppresses the immune system. Tuberculosis (TB) and hepatitis B are the infections that most frequently recur after starting this medication. For this reason, patients are screened for infection with TB or hepatitis before starting this treatment regimen. Yearly protein purified derivative (PPD) skin tests for TB are given after starting infliximab to monitor for ongoing exposure to TB.

As the medication decreases the activity of the immune system, some other types of infliximab side effects can also occur. Patients are at an increased risk for new infections. Some of these infections — such as upper respiratory tract infections, sinusitis, and urinary tract infections — can be mild, and either resolve without treatment or are easily cured with antibiotics. Other infections, however, are more serious. Certain pathologic organisms such as fungi target patients with lowered immune function, and can cause significant complications.

Rarely, infliximab can cause decreases in patients' blood counts. Red blood cells, white blood cells, and platelets can decrease in number due to use of the drug. Reduced numbers of these cells can cause severe side effects and can even be life-threatening in some cases. For this reason, patients on inflixamab therapy have their blood counts checked regularly to monitor for downward trends.

Ongoing treatment with infliximab can also put patients at risk for developing certain cancers later in life. The most common malignancies seen in patients are lymphomas, either of the Hodgkin's or the non-Hodgkin's type. Patients given the medication to treat inflammatory bowel disease are at an increased risk for developing hepatosplenic T-cell lymphoma. Some studies have also shown an increased incidence of non-melanoma skin cancers in patients taking the drug.