Immunotherapy and Confusion: What to Know and How to Cope

Yes, confusion can occur with immunotherapy, although it is uncommon. Confusion may arise from immune-related effects on the brain (encephalitis or meningitis), hormone gland problems (like thyroid or pituitary inflammation), infections, or medication side effects. ^[1] Cognitive changes including memory problems and trouble focusing can also be linked to certain cancer treatments and supportive medicines. ^[2]

How Immunotherapy Can Lead to Confusion

Immune-related inflammation of the brain (encephalitis) or the meninges (meningitis) is a rare but serious cause of confusion. These conditions may present with headache, fever, neck stiffness, sensitivity to light, hallucinations, or severe muscle weakness alongside confusion. ^[1] Similar symptom lists are recognized across patient education resources, highlighting confusion and memory problems as potential signs. ^[3]

Hormonal (endocrine) adverse effects from immunotherapy such as inflammation of the pituitary (hypophysitis) or adrenal glands can also trigger confusion. Endocrine emergencies like adrenal crisis can cause decreased consciousness, lethargy, seizures, and hyponatremia; urgent steroid treatment and endocrine evaluation are advised. ^[4] In hypophysitis, acute symptoms may include dizziness, headache, severe fatigue, and confusion; management involves withholding immunotherapy and full endocrine workup. ^{[5] [6]}

Other contributors to cognitive changes in people with cancer include medications (immunotherapy, pain medicines, antibiotics, antinausea drugs), anemia, sleep problems, fatigue, and high calcium levels. These factors can combine to produce forgetfulness, slowed thinking, or confusion. ^[2] Guidance on managing cognitive changes acknowledges both treatment-related and non-treatment-related causes. ^[7]

Red Flags: When to Seek Urgent Care

Seek emergency care right away for confusion with any of the following:

• New or worsening headache, high fever, neck stiffness, severe sensitivity to light, hallucinations, or muscle weakness (possible meningitis/encephalitis). ^[1]
• Decreased consciousness, seizures, fainting, severe lethargy, or suspected low blood sugar or sodium (potential adrenal crisis or severe endocrine toxicity). ^[4]
• Rapidly escalating symptoms or inability to perform normal activities; immunotherapy should typically be withheld during evaluation. ^[8]

Practical Coping Strategies

1. Report symptoms promptly and keep a symptom log. Early assessment helps distinguish causes like brain inflammation, endocrine issues, medication effects, or metabolic problems. ^[8] Noting timing relative to infusions and new medications can guide your care team. ^[9]

2. Get screened for reversible causes. Your team may check endocrine labs (morning cortisol, thyroid function), electrolytes (sodium, calcium), infection workup, and, if needed, brain imaging or spinal fluid tests to rule out serious inflammation. ^[6] If an endocrine emergency is suspected, steroids may be started urgently and tapered as you stabilize. ^[4]

3. Adjust medications that affect thinking. Some supportive drugs (pain relievers, anti-nausea agents, antibiotics) can cloud thinking; careful review and dose adjustments can help. ^[2] Cognitive side effects from various treatments are recognized, and individualized plans often reduce symptoms. ^[7]

4. Use daily cognitive supports.

• Create structured routines and checklists to reduce memory load. ^[7]
• Use reminders (phone alarms, sticky notes) and keep important items in designated spots. ^[7]
• Pace activities, schedule demanding tasks when energy is highest, and take short, regular breaks. ^[7]
• Prioritize sleep hygiene and gentle physical activity to combat fatigue-related “brain fog.” ^[7]

5. Manage stress and mood. Anxiety around scans and treatment can worsen cognitive symptoms; evidence-based coping strategies and counseling can reduce distress and improve focus. ^[10]

6. Collaborate on treatment decisions. Depending on the cause and severity, your team may temporarily hold immunotherapy, start steroids or other immunosuppressive treatments, and resume therapy once stabilized. Close monitoring is important, and rapid improvement after appropriate treatment should occur; if not, the diagnosis may need review. ^[8]

What Recovery Looks Like

Most cognitive symptoms improve when the underlying cause is identified and treated especially endocrine problems or medication effects. For immune-related brain inflammation, recovery varies; early recognition and treatment are key to better outcomes. ^[8] Patients often benefit from a combined approach medical management plus practical cognitive strategies and stress reduction techniques. ^{[7] [10]}

Bottom Line

Confusion with immunotherapy is possible but uncommon; it can be driven by immune-related brain or endocrine effects, infections, or medications. Recognizing warning signs and seeking timely medical evaluation are essential, and practical coping strategies can help day-to-day functioning while your team treats the root cause. ^{[1] [4] [2] [8]}