Can Immunotherapy Cause Fever and How to Manage It

Yes, fever can occur with cancer immunotherapy, and it’s a recognized side effect across several immunotherapy types. A temperature of 100.4°F (38°C) or higher is a threshold at which you should contact your care team. ^[1] Fever may present with chills and other flu‑like symptoms, and it can be related to immune activation, infection, or less commonly immune effector toxicities like cytokine release syndrome (CRS). Flu‑like symptoms such as chills, fatigue, and fever are common with biological therapies that stimulate the immune system. ^[2] Educational guidance for immunotherapy patients consistently advises calling your provider at 100.4°F (38°C) or above, especially if accompanied by shaking, new cough, sore throat, or burning with urination. These associated symptoms can signal an infection that needs prompt evaluation. ^[1]

Why Fever Happens with Immunotherapy

• Immune activation: Some immunotherapies stimulate your immune system to attack cancer, which can produce inflammatory signals causing fever and flu‑like symptoms. ^[2]
• Infection risk: While your immune system is being modulated, infections can occur; fever with localizing signs (new cough, sore throat, burning when urinating, redness or pus near a wound) suggests infection and needs prompt care. Report these symptoms if present with fever. ^[1]
• Specific drug-related syndromes: Certain targeted combinations (e.g., BRAF/MEK inhibitors like dabrafenib + trametinib) can cause a non‑infectious “fever syndrome” with rigors, dehydration, dizziness, and fatigue. Early dose interruption and symptomatic treatment usually resolve fever within 24 hours in uncomplicated cases. ^[3]

When to Call Your Care Team

• Fever ≥100.4°F (38°C), or shaking/chills, should prompt a call to your provider. ^[1]
• Fever plus signs of infection (redness, swelling, warmth, pus at a wound or catheter site; new cough; sore throat; burning with urination) needs urgent evaluation. ^[1]
• For patients receiving CAR T‑cell therapy, any fever at or above 100.4°F (38°C) requires immediate urgent care, due to the risk of CRS. ^[4] CAR T guidance highlights that fever with flu‑like symptoms is common after infusion and warrants close monitoring. CRS can begin with fever and progress to low blood pressure or low oxygen prompt care reduces risks. ^[5]

Practical Self‑Care Steps at Home

• Confirm your temperature: Use a reliable thermometer; recheck if you feel feverish or develop chills. Keep a log to share with your care team. ^[1]
• Hydration and rest: Drink fluids and rest to support recovery; dehydration can worsen dizziness and fatigue seen in fever syndromes. This is particularly helpful during non‑infectious fevers. ^[3]
• Symptom relief: Acetaminophen (paracetamol) or NSAIDs may help reduce fever and aches if your clinician has said they’re safe for you. These are commonly used during pyrexia to ease symptoms. ^[3]
• Watch for infection signs: New cough, sore throat, burning with urination, or redness/pus at surgical or catheter sites should prompt calling your provider. These signs increase concern for infection alongside fever. ^[1]

Special Situations: CRS and CAR T

• CRS basics: CRS often starts with fever ≥38°C and may include hypotension (low blood pressure) or hypoxia (low oxygen). Severity is graded by the presence of low blood pressure and/or low oxygen in addition to fever. ^{[6] [7]}
• Initial management for mild CRS (grade 1): Antipyretics like acetaminophen or ibuprofen if appropriate, infection screening, and empiric broad‑spectrum antibiotics as directed; IV fluids help with hydration. Escalation to tocilizumab or steroids is considered if symptoms progress. ^[8]
• Post‑treatment grading: After antipyretics or anti‑cytokine therapy, fever may no longer be required for grading; low blood pressure or low oxygen then drive severity grading. ^[9]

What Your Care Team Might Do

• Assess for infection: They may order labs, imaging, and cultures if infection is suspected; infection workup is prioritized when fever has localizing symptoms. ^[1]
• Hold or adjust therapy: With certain targeted therapies (e.g., dabrafenib + trametinib), temporary dose interruption can rapidly resolve non‑infectious fever and therapy can resume 24 hours after fever resolves. ^[3]
• Treat immune‑related toxicity: For CRS or severe immune activation, clinicians may use IV fluids, antipyretics, antibiotics if infection is possible, and targeted therapies like tocilizumab or corticosteroids when indicated. ^[8]

Red Flags That Need Urgent Care

• Fever ≥100.4°F (38°C) plus any of the following: shaking/chills, confusion, breathing trouble, dizziness/lightheadedness, chest pain, very fast heart rate, low blood pressure, or oxygen problems. These can signal CRS or serious infection and need immediate attention. ^{[1] [5]}
• CAR T recipients: Go to urgent care as instructed if you develop fever ≥100.4°F (38°C); call your cellular therapy unit while en route. ^[4]

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Quick Reference: What to Do for Fever on Immunotherapy

• Fever ≥100.4°F (38°C): Call your care team. ^[1]
• Chills or shaking: Call your care team. ^[1]
• Signs of infection (redness/pus at wound/catheter, new cough, sore throat, burning urination): Call your care team promptly. ^[1]
• Hydration, rest, and antipyretics if approved: Helpful for symptom relief. ^[3]
• CAR T patients: Seek urgent care for any fever ≥100.4°F (38°C) right away and notify your team. ^{[4] [5]}

Keeping a simple symptom diary (time, temperature, medication taken, associated symptoms) can help your clinicians tailor advice and treatment. Consistent monitoring and early communication with your team are key to safe, effective management of fever during immunotherapy. ^{[1] [4] [3]}