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Imfinzi

Imfinzi Side Effects

Julia Lee, PharmD, BCOPDaisy Chau, PharmD
Reviewed by Julia Lee, PharmD, BCOP, Daisy Chau, PharmD
Last reviewed on May 5, 2026

The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.

Common Side Effects

  • High blood sugar (52%)
  • Low calcium levels (46%)
  • Low white blood cell count (43%)
  • Cough (40%)
  • Rise in liver enzymes (up to 39%)
  • Lung inflammation (34%)
  • Fatigue (34%)
  • Low sodium levels (33%)
  • High potassium levels (32%)
  • Upper respiratory tract infections (26%)
  • Shortness of breath (25%)
  • Rash (23%)

Note: Side effects above were reported in people with NSCLC who took [[EDITOR|DRUG_DISPLAY_NAME]] alone

Less Common Side Effects

  • Diarrhea
  • Pneumonia
  • Fever
  • Itching
  • Low thyroid levels
  • Stomach pain
  • Hoarseness
  • Painful urination
  • Night sweats
  • Swelling in the arms and legs
  • Infections

Imfinzi serious side effects

Contact your healthcare provider immediately if you experience any of the following.

  • Immune-related side events: rash, blisters, skin peeling, diarrhea, trouble breathing, coughing, chest pain, severe stomach pain, mucus or blood in stool, headache, reduced appetite
  • Infusion-related reactions: chills, fever, itching, rash, trouble breathing, flushing, dizziness, fainting, back or neck pain

Source: DailyMed

The following Imfinzi side effects have also been reported

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Dry cough, shortness of breath or trouble breathing
  • Eye pain, redness, irritation, or discharge with blurry or decreased vision
  • Heart muscle inflammation—unusual weakness or fatigue, shortness of breath, chest pain, fast or irregular heartbeat, dizziness, swelling of the ankles, feet, or hands
  • Hormone gland problems—headache, sensitivity to light, unusual weakness or fatigue, dizziness, fast or irregular heartbeat, increased sensitivity to cold or heat, excessive sweating, constipation, hair loss, increased thirst or amount of urine, tremors or shaking, irritability
  • Infusion reactions—chest pain, shortness of breath or trouble breathing, feeling faint or lightheaded
  • Kidney injury (glomerulonephritis)—decrease in the amount of urine, red or dark brown urine, foamy or bubbly urine, swelling of the ankles, hands, or feet
  • Liver injury—right upper belly pain, loss of appetite, nausea, light-colored stool, dark yellow or brown urine, yellowing skin or eyes, unusual weakness or fatigue
  • Pain, tingling, or numbness in the hands or feet, muscle weakness, change in vision, confusion or trouble speaking, loss of balance or coordination, trouble walking, seizures
  • Rash, fever, and swollen lymph nodes
  • Redness, blistering, peeling, or loosening of the skin, including inside the mouth
  • Sudden or severe stomach pain, bloody diarrhea, fever, nausea, vomiting

Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):

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