Fever and Lung Cancer Treatment: Causes, Risks, and Management

Fever can occur during lung cancer treatment, and its meaning depends on the therapy and timing. ^[1] People receiving chemotherapy should treat any fever as a possible medical emergency because it can be the first and only sign of a serious infection. ^[1] Fever can also be related to the cancer itself or to inflammation from immunotherapy, while radiation more commonly causes fatigue and throat irritation rather than fever. ^{[2] [3]}

Why fever happens

• Chemotherapy and infections: Chemotherapy lowers white blood cells (especially neutrophils), which weakens the body’s defenses; in this setting, fever may be the earliest sign of infection and needs urgent attention. ^[1] Clinicians often presume infection first and start antibiotics promptly until low infection risk is proven. ^[4]
• Immunotherapy (checkpoint inhibitors): These medicines can trigger immune reactions that feel “flu‑like,” with chills, fatigue, and sometimes fever due to inflammation rather than infection. ^[2] Immune‑related side effects are common across checkpoint inhibitors and require specific evaluation and management. ^[5]
• Radiation therapy: Short‑term effects more often include skin irritation, fatigue, and swallowing pain; fever is less typical with radiation alone. ^[3]
• Cancer‑related fever: Tumors can release substances that raise body temperature, and infection remains a frequent and potentially serious cause of fever in people with cancer. ^[6]

When fever is urgent

• During or after chemotherapy: Any fever should be treated as an emergency; take your temperature whenever you feel warm, flushed, chilled, or unwell, and call your care team immediately. ^[1]
• High‑risk groups: People with cancer have higher risk from influenza and other infections; fever should prompt timely medical contact. ^[7]
• Suspected neutropenia (low neutrophils): Health teams manage fevers as neutropenic until proven otherwise, with rapid antibiotics and cultures. ^{[4] [8]}

What to do right away

• Check temperature and call: If temperature is 38.0°C (100.4°F) or higher, contact your oncology team or go to urgent care/emergency services, especially if you are on or recently finished chemotherapy. ^[1]
• Do not delay antibiotics in suspected neutropenic fever: Clinicians aim to give antibiotics within 30 minutes for unstable patients and within 1 hour for stable patients after drawing cultures. ^[8]
• Get cultures and evaluation promptly: Blood cultures and focused exams (mouth, skin, urinary tract, injection/biopsy sites, IV lines) help find infection sources; treatment is reassessed daily. ^{[9] [10]}
• Low‑risk vs high‑risk triage: Teams may use validated tools (such as the MASCC index) to identify who can be treated as an outpatient versus who needs admission. ^[11]

How doctors manage fever

• Empiric antibiotics: Initial broad‑spectrum antibiotics are started fast and tailored once labs and cultures guide therapy; combinations or monotherapy are chosen based on stability and allergies. ^{[10] [12]}
• Supportive care and monitoring: Daily review of antibiotic appropriateness, lab checks, and imaging as indicated are routine until infection resolves and counts recover. ^[10]
• Growth factors: In some cases, injections that stimulate white blood cell production may be used to reduce the duration of neutropenia. ^[6]
• Immunotherapy‑related fever or inflammation: If immune side effects are suspected, clinicians may pause treatment and use steroids or other measures per immune‑related adverse event protocols. ^[5]
• Radiation‑related symptoms: Management typically focuses on skin care, nutrition, and symptom relief; fever suggests looking for other causes like infection. ^[3]

Practical steps you can take

• Know your plan: Ask your team for a written “fever action plan,” including who to call 24/7 and where to go if symptoms escalate. ^[1]
• Track symptoms: Note timing relative to infusions, associated chills, cough, pain on swallowing, shortness of breath, or local redness around lines these clues help triage infection vs inflammation. ^{[1] [9]}
• Vaccination and prevention: Seasonal flu and pneumococcal vaccines are generally recommended in cancer care to reduce infection risks; your provider will advise which are right for you. ^[7]
• Home safety: Good hand hygiene, mouth care, and watching for redness at catheter or injection sites can help catch problems early. ^[6]

Special notes for immunotherapy

• Flu‑like symptoms possible: Chills, fatigue, and fever can occur due to immune activation; report new or worsening symptoms promptly, as early management prevents complications. ^{[2] [5]}
• Combination regimens: When immunotherapy is given with chemotherapy (e.g., carboplatin/paclitaxel plus nivolumab), fevers require careful evaluation for both infection and immune‑related causes. ^[13]

Bottom line

Fever during lung cancer treatment is not rare, but its meaning varies: infection is common and can be dangerous during chemotherapy, while immunotherapy can cause inflammatory fevers, and radiation less often causes fever. ^{[1] [2] [3]} The safest approach is to treat any fever during chemotherapy as urgent, contact your team immediately, and let clinicians rapidly evaluate and start appropriate therapy. ^{[1] [8]}