screening for fever

Overview

A fever is a body temperature that is higher than normal. It is not an illness on its own — it is a sign that the body's immune system is fighting an infection. Most fevers are short-lived and harmless, but knowing how to check for fever and when to seek help is important, especially for babies, children, and older people.

Fever is very common. It is one of the most frequent reasons for visiting a doctor, especially for parents with young children. Most people will experience a fever several times during their life.

Fever can affect anyone, but it is more common in children under 5 because their immune systems are still developing. It can also affect older adults more severely, and people with long-term health conditions or weakened immune systems are more prone to infections that cause fever.

Symptoms

Common symptoms

• A body temperature above the normal range (often 38°C or 100.4°F when taken by mouth)
• Feelings of being hot or cold, chills, or shivering
• Sweating, flushed skin, and muscle aches

Symptoms in children

• Irritability, fussiness, or crying more than usual
• Being hot to the touch, especially on the forehead, back, or tummy
• Poor appetite, drinking less, or sleeping more than usual
• A fit or seizure during a fever (call your local emergency number if this happens)

Symptoms in older adults

• Confusion or sudden changes in behaviour or alertness
• Weakness, fatigue, or a general feeling of being unwell
• Loss of appetite or reduced drinking
• It is possible to have a serious infection with a normal or even low temperature, so look out for any change in their usual condition

Causes

Main causes

• Infections — most commonly viruses and bacteria, such as colds, flu, chest infections, or urine infections
• Vaccination, as the body's immune system responds to the vaccine by making a mild fever
• Heat exhaustion from being too hot, or inflammatory conditions such as rheumatoid arthritis
• Some medicines can cause a fever as a side effect

Risk factors

• Very young age, especially babies under 3 months
• Older age, especially over 65 or if frail
• A weakened immune system from a long-term illness or medical treatment
• Long-term conditions such as diabetes, heart disease, or lung disease
• Recent travel to areas where certain infections are common

When to see a doctor

See a doctor urgently if:

• A baby under 3 months old with any fever
• A fever with a severe headache, stiff neck, or a rash that does not fade when pressed
• Difficulty breathing or swallowing
• A seizure or convulsion
• Confusion, unusual sleepiness, or being hard to wake

Book a routine appointment if:

• A fever that does not improve after a few days
• A high fever that keeps returning
• A fever with vomiting, diarrhoea, or signs of dehydration
• A fever in someone with a long-term condition or weakened immune system
• If you are worried, or the fever is not behaving as you would expect

Diagnosis

A healthcare professional will measure the person's temperature using a thermometer — usually in the ear, under the tongue, under the arm, or on the forehead. They will also ask about the person's symptoms, medical history, and any close contact with unwell people. A physical examination helps look for signs of infection, such as a sore throat or a chest infection.

Tests that may be done

• Blood tests to look for signs of infection or inflammation
• Urine tests to check for a urine infection
• Throat or nasal swabs to test for certain viruses or bacteria
• Chest X-ray if there is a cough or breathing difficulty

What to expect at your appointment

The check is usually quick and straightforward. The doctor or nurse may ask when the fever started, how high the temperature has been, and whether there are other symptoms. For a baby or young child, the doctor may also check their alertness, skin, and level of hydration. You do not need to bring anything special, but it can help to note down temperatures and symptoms at home.

Treatment

The main aim of fever treatment is to make the person comfortable and to treat the cause of the fever. Most fevers are short-lived and can be managed at home with rest and fluids. If a bacterial infection is found, a doctor may prescribe antibiotics. For viral infections, the body usually heals itself with time.

Self-care at home

• Rest and sleep until the fever settles
• Drink plenty of fluids — water, clear soups, or approved oral rehydration drinks — in small, regular sips
• Wear light clothing and keep the room at a comfortable, cool temperature
• Ask your pharmacist or doctor whether a fever-reducing medicine is suitable, and always follow their dosing advice

Medical treatments

For a bacterial infection, antibiotics may be prescribed to treat the underlying cause. For viral infections, supportive care is the main approach. Fever-reducing medicines (called antipyretics) can improve comfort, but they do not kill viruses or bacteria. Never give these medicines to a child without checking the correct dose for their age and weight with a pharmacist or healthcare professional.

When is surgery considered?

Surgery is not used to treat fever itself. If an internal infection such as appendicitis or an abscess is the cause, surgery may be needed to treat that infection. This is uncommon, and a doctor would discuss it clearly if it became relevant.

Living with this condition

While someone has a fever, focus on keeping them comfortable and observing for warning signs. Check their temperature regularly, encourage small amounts of fluids, and let them rest. Track how they are feeling — whether they are drinking, urinating, and responding normally. This information is useful if you need to speak with a doctor.

Lifestyle tips

• Keep a child home from school or nursery until the fever has gone for at least 24 hours
• Wash hands frequently, especially after contact with the unwell person, to reduce the spread of infection
• Use separate towels and cups if possible, and open a window for fresh air
• Avoid intense exercise or sports until the fever has fully settled

Diet and exercise

Eat light, easy-to-digest foods if you feel hungry, such as toast, rice, bananas, or plain soups. Do not force food, especially in children. While feverish, avoid heavy exercise — the body needs energy to fight the infection. When the fever has gone, gradually return to normal activity as you feel able.

Mental health and emotional wellbeing

A fever — particularly in a child or an older relative — can be stressful and unsettling. Worry about when to act is completely natural. Keep in mind that most fevers are brief and resolve well. If you feel anxious or overwhelmed, speak with a local health professional. Reaching out for reassurance and advice is always a sensible step.

Prevention

Not all fevers can be prevented, but you can reduce the chance of infections that cause them. Regular handwashing with soap and warm water, covering coughs and sneezes, avoiding close contact with unwell people, and following recommended vaccination schedules all help lower the risk.

Vaccines

Vaccination is one of the best ways to prevent serious infections that can cause fever. This includes routine childhood immunisations, the annual flu vaccine if recommended for you, and any vaccines your health professional suggests because of your age, health, or travel plans.

Screening programmes

At home, you can screen for fever using a simple digital thermometer. For babies and children, an under-the-arm or forehead reading is easier and less upsetting. Healthcare teams also measure temperature as part of routine checks to spot infection early. If you notice a fever, record it along with any other symptoms and monitor how the person is generally feeling.

Complications

If left untreated

• Dehydration, especially in babies, young children, and older adults
• Febrile seizures in young children (convulsions brought on by a rapid rise in temperature)
• A spreading infection, which can become a serious whole-body response such as sepsis
• Confusion, extreme tiredness, or worsening unwellness in older adults

Long-term outlook

The outlook for most fevers is very good. The large majority of fevers are caused by short-lived infections and settle within three to five days as the body recovers. Even with more serious infections, early medical care and appropriate treatment help most people improve completely. Remember that fever is a sign the immune system is working — and knowing when to watch, rest, and seek help makes a real difference.

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