Why does a common cold cause fever?

A fever is part of the body's response to infection. Immune signals act on the brain's temperature-control centre, making the body conserve heat and produce more of it. That is why you may shiver or feel cold as the temperature rises, then sweat as it falls. Fever is a common presentation of Common Cold, though fever also occurs with many infections and non-infectious conditions.

The number on a thermometer is only one part of the picture. How you look and feel, your breathing, alertness, fluid intake, age, health conditions, and the course of the illness all matter when deciding whether to seek care.

Rest, wear light comfortable clothing, and drink regularly. Take small sips more often if a sore throat or nausea makes drinking difficult. Keep the room comfortably cool and avoid trying to force a temperature down with ice baths or very cold water, which can cause shivering and greater discomfort.

If you choose a fever medicine, follow the label carefully and check with a pharmacist if you take other products for a cold, because ingredients can overlap. Children need products and doses appropriate to their age and weight; do not use adult medicines as a substitute.

Seek urgent care for difficulty breathing, chest pain, a seizure, confusion, a severe headache with neck stiffness, a non-blanching rash, or marked sleepiness. Obtain medical advice promptly for fever with dehydration, persistent vomiting, a worsening overall condition, or a new focal symptom such as severe ear pain. Babies and young children with fever need age-specific guidance, and people who are pregnant, immunocompromised, or have serious long-term illness should seek advice early.

Tell the clinician how the temperature was measured, when it started, and whether it comes with rash, cough, pain, or urinary symptoms. Ask which changes would make reassessment necessary and which medicines are safe alongside your regular treatment.