Fever is widely seen as the body’s most dependable alarm for infection. But in older adults, this signal can be faint, delayed—or missing altogether. Doctors warn that this makes infections in the elderly far more difficult to detect, often leading to dangerous delays in treatment.
Highlighting the risks of such atypical presentations, Dr. Prasun Chatterjee, Group Clinical Lead, Dept. of Geriatric Medicine and Longevity Sciences, Apollo Hospital Group, recalled a recent case from his outpatient department. “A 70-year-old woman had come in with what appeared to be relatively mild complaints. She had no fever, and her family believed her condition was not serious.”
Yet, her clinical condition told a different story. The patient was breathless even while seated, and examination revealed swelling and redness in her leg—signs that pointed to a deeper underlying problem. Despite the absence of fever, further evaluation confirmed that she was suffering from an advanced infection that had already begun to spread, said Dr. Chatterjee.
She was immediately admitted and treated with intravenous antibiotics. With timely intervention, she recovered, but the delay in recognising the severity of her illness could have proved fatal.
“Fever is not a reliable marker of infection in the elderly. By the time more obvious symptoms appear, the disease may already be at an advanced stage,” explained Dr. Chatterjee. “In such patients, even subtle signs like breathlessness, swelling, or a general sense that something is ‘not right’ must be taken seriously.”
Doctors say such cases are becoming increasingly common as India’s population ages, reflecting a broader challenge in geriatric care.
A research study by Dr. Baldeep Kaur and colleagues from Dr. B. R. Ambedkar State Institute of Medical Sciences (AIMS), Mohali, published in the Journal of the Indian Academy of Geriatrics, highlights how ageing alters the body’s response to infection. Weak immune systems and multiple coexisting illnesses often mask classic symptoms such as fever.
Instead, infections in older adults may present through vague and non-specific signs—confusion, fatigue, loss of appetite, or a sudden decline in daily functioning, they noted.
Explaining the science behind this, Dr. Ivayla Geneva, an infectious disease specialist in Syracuse, New York, said ageing affects the body’s ability to regulate temperature.
“As we age, we have a slower metabolic rate and are unable to maintain normal body temperature,” explained the lead author of a systematic review on normal temperature for the elderly published in the journal Open Forum Infectious Diseases.
“These changes are important clinically because we know older patients have weaker immune systems, difficulty fighting off infection and disease, and often fail to reach the temperature range of what is traditionally considered a fever—anything above 100.4 F.”
Experts say this blunted response means that even serious infections may not trigger a high temperature.
Dr. Ajaya Kumar, Director, Medical Services at Apollo Hospitals, Lucknow, echoed similar views, noting that fever may be absent in a significant proportion of elderly patients.
“Fever may be absent in as many as 30 to 50% of older adults even in the presence of serious infections. Instead, symptoms may appear in subtle and indirect forms such as behavioural changes, lethargy, loss of appetite, or slurred speech,” he said.
He added that the body’s thermoregulation mechanisms—including shivering, vasoconstriction, and hypothalamic control—become less effective with age, making it harder to mount a typical fever response.
Doctors emphasised that managing infections in the elderly requires a high degree of clinical suspicion. Treating symptoms like mild fever without proper evaluation can delay diagnosis and worsen outcomes.
Polypharmacy—the use of multiple medications—adds another layer of complexity. Many elderly patients take several drugs, increasing the risk of side effects and interactions that can mask or mimic infection symptoms.
Communication barriers can further delay diagnosis. Older patients, especially those with dementia or cognitive decline, may not be able to clearly describe what they are feeling. This makes it harder for both families and doctors to recognise early warning signs.
Experts say families play a crucial role in early detection. Sudden changes in behaviour, sleep, appetite, or mobility should never be ignored.
“A general sense that something is ‘not right’ is often the first clue,” doctors said. What may seem like routine ageing could actually be the early stage of a serious illness.
Even measuring temperature in elderly patients requires care. Further, the Centers for Disease Control and Prevention (CDC) notes that “non-contact infrared thermometers, frequently used for health screening, must be held at a certain distance from the temporal artery in the forehead to take the temperature correctly. Holding the device too far from or too close to the temporal artery affects the reading.”
Infections such as pneumonia, urinary tract infections, and skin infections remain common among older adults in India. Early recognition is critical to prevent complications, reduce hospital stays, and lower both health risks and treatment costs.
Preventive care is equally important. Vaccination against influenza and pneumonia, regular health check-ups, and maintaining hygiene can significantly reduce the risk of infections in this vulnerable group.
Doctors say the takeaway is simple but crucial: waiting for fever in elderly patients can be dangerous.
As Dr. Chatterjee emphasised, subtle warning signs should never be ignored. “Recognising these early can make the difference between timely recovery and a life-threatening emergency.”
