At the high doses approved for melanoma treatment, interleukin-2 may cause a variety of severe side effects, including:

• Low blood pressure
• Difficulty breathing
• Abnormal kidney and liver function
• Bone marrow suppression, leading to a shortage of red and white blood cells
• Changes in thyroid function

At lower doses, the most commonly reported side effects include:

• Flu-like symptoms within 1 to 4 hours of injection: fever, chills, muscle and joint aches, nausea, and vomiting
• Fatigue skin rashes
• Mouth sores
• Loss of appetite
• Diarrhea

As with most medications, the chances of developing side effects from interleukin-2 therapy are dependent on dose, with higher doses tending to produce more severe and consistent side effects. Often, the most severe side effects occur during the first few weeks of therapy and then taper off significantly.

If you are having severe side effects, talk to your doctor. Treatments are available to relieve symptoms such as nausea and fatigue. You will also receive careful and continuous monitoring for life-threatening side effects, including bone marrow suppression and kidney or liver damage. Many side effects are generally reversible when therapy is stopped. If the symptoms or signs are significantly abnormal, the treatment may be interrupted for a time, and then resumed at a lower dose. Throughout the course of the therapy, treatment may be stopped and restarted at different dosages as needed.

Contact your doctor immediately if, after treatment, you experience any of the following serious side effects:

• A decrease in urine production
• Persisting swelling of the face, neck, hands, or feet
• A sustained fever of 100.5° F (38.1°C)
• Lightheadedness or dizziness upon standing
• Palpitations or chest pain
• Difficulty breathing
• Confusion, disorientation, or impaired memory