A fever is when your body temperature rises to become higher than normal. The average, normal human body temperature is 37°C (98.6°F).

For most adults and children, a temperature of 37.5 °C and above is considered a fever. Any temperature above 38.5 °C is considered a high fever.

You can’t use your hand to ‘test’, ‘estimate’ or check for a fever. Only a thermometer can measure your temperature accurately. 

What kind of thermometers can you use?

• Ear: The thermometer is put into the ear canal. You’ll need to ensure the thermometer probe fits properly inside to get an accurate reading.
  
  
• Forehead: These are called temporal artery thermometers, and you might be familiar with them being used in clinics and public places during the COVID-19 pandemic.
  
  
• Mouth: The thermometer tip is placed under your tongue to take a reading.
  
  
• Armpit: The thermometer is placed in the centre of the armpit to take a reading.
  
  
• Rectal: This is considered the most accurate form of measurement and is recommended for infants 6 months old and below. The thermometer is gently inserted into the rectum to get a reading. 

While fever can make you feel uncomfortable, it may be a sign that your immune system is fighting an infection to help you get better.

“Fever is not a disease, but rather a symptom. It can point to a wide range of underlying causes, from infections to autoimmune conditions, hence it is important to understand the root cause of the fever,” said Dr Aloysius Lam, Family Physician, and Member of Infection Prevention and Infectious Disease Committee from SingHealth Polyclinics (SHP).

SHP is a member of the SingHealth group.

Common fever symptoms include:

• Skin feeling hot to the touch
  
• Flushed cheeks (your face might look redder than normal)
  
• Sweating (this tends to happen when the fever breaks or ends)
  
• Shivering (feeling cold, even when you’re not in a cold place)
  
• Aching, tender muscles and joints
  
• Poor appetite
  
• Feeling dehydrated
  
• Feeling irritable
  
• Feeling tired 

Depending on the cause of the fever, you might get fever symptoms with other indications. 

For example, someone with COVID-19 infection might experience fever with flu-like symptoms (cough, runny nose and sore throat).

Gastroenteritis (food poisoning) might cause fever symptoms, diarrhoea and vomiting.

Most fevers, especially mild fevers resolve on their own after you get enough rest. Home remedies can help you manage the uncomfortable symptoms while you recover.

1. Drink more water 

You might feel dehydrated while having a fever due to water loss from sweating and breathing. If you’re down with gastroenteritis, the vomiting and diarrhoea might make your dehydration worse. 

Staying hydrated helps manage fluid loss and dehydration that happens during a fever. It prevents the dangers of dehydration, like low blood pressure and giddiness.

Drink plenty of fluids like plain water, fruit juice, or clear broth.

Your body also loses salts and minerals from sweating. Replenish lost salts and electrolytes with a packet of oral rehydration salts - your doctor might give you these, or you can buy them from any local retail pharmacy. 

You can also try boiled barley or rice water with a little salt sprinkled in.

2. Wear light clothing 

Your body perspires more when the fever breaks. Wear light clothing of breathable or sweat-wicking fabrics (sports or exercise clothes), which will keep you cool.

3. Get enough rest at home 

Some people may feel fine when having a mild fever and will want to continue with their daily activities. However, it is important to have sufficient rest to recover.

Stay in a well-ventilated room with the windows open. You can keep a fan switched on at low speed to prevent excessive sweating. 

If you’re shivering, cover yourself with a light blanket or towel. Do not use quilts and blankets, as these could make you sweat more.

You may also want to use cool and damp towels to help you feel better. Wet the towels with some tap water, squeeze them dry, and place them on your forehead, the back of your neck, and armpits. Leave them on for about 5 minutes.   

4. Take lukewarm baths 

Take lukewarm baths with a basin of lukewarm water and a wash towel. Gently sponging your skin with slightly warm water can help to cool the fever while making sure the water temperature does not worsen your shivering.

5. Take over-the-counter medications 

Fever can be treated using the following medications which are available over the counter. You can ask your pharmacist to recommend a suitable medication.

• Paracetamol
• Ibuprofen

Both can help relieve pain and temporarily bring the fever down to help you feel better. Take your medications as recommended on the packet, and do not exceed the recommended dosage. 

For adults, see a polyclinic doctor or family GP if:

• Your fever is 38.5°C and above.
• The fever lasts for longer than 3 days.
• You have a fever while pregnant.
• You have a fever just after returning from overseas.
• You have existing medical conditions like asthma, kidney disease, liver disease, heart disease and diabetes.
• You are taking medications which suppress the immune system. 

For children and infants, bring them to see a doctor if:

• Their fever is above 41°C, or above 37.5°C for those younger than 3 months old.
• Their fever last for more than 3 days.
• They appear drowsy and difficult to awake.
• They seem confused.
• They are very irritable or cry constantly, and cannot be soothed or comforted.
• They have a seizure.
• They are drinking less fluids or have lower urine output than usual.
• They have difficulty in breathing.
• They have unstoppable vomiting with a stiff neck or severe headache.
• They start developing rashes or unexplained bruise-like spots.

The common causes of fever are infections include:

• Common cold
• Influenza (flu)
• COVID-19
• Gastroenteritis (food poisoning)
• Urinary tract infections (UTI)
• Dengue

Less common causes include:

• Heat exhaustion
• Hormonal disorders e.g. hyperthyroidism (a condition where your body makes too much thyroid hormone)
• Autoimmune conditions (conditions whereby your immune system attacks your body’s tissues by mistake)
• Cancer
• Vaccines
• Post vaccination side effect
• Certain medications

Fever is usually the body’s natural reaction to infections. However, fever can sometimes be a sign of something more serious. 

Go to the Accident & Emergency Department if the following symptoms are present:

• Confusion
• Irritability
• Fits or seizures (a shaking body, clenched jaw, eyes rolling upwards)
• Vomiting that doesn’t stop
• Unusual skin rash (or a skin rash that worsens)
• Unusual sensitivity to bright lights
• Coughed up blood
• Difficulty breathing
• Chest pain
• Severe headache
• Severe neck pain
• Severe back pain 

“Fever can be concerning when it is accompanied by symptoms like confusion, difficulty breathing, or extreme weakness.

In these cases, it is best to get medical attention as soon as possible to rule out life-threatening conditions,” said Dr Isabelle Yoong, Family Physician, and Member of Infection Prevention and Infectious Disease Committee, SHP.

Use these tips to manage your symptoms and get enough rest at home. If you have seen a doctor, take your medication as prescribed and rest until the fever breaks.

Ref: G25

Related articles: 
Cold and Flu (Influenza): Causes, Differences and Treatment

How to Reduce Phlegm and Mucus

Pneumonia: How to Prevent and Treat

The content above is solely for informational purposes only and is not intended as a substitute for the advice provided by your physician, pharmacist or other healthcare professional. You should not use the information for diagnosing or treating a health problem or disease or prescribing any medication or other treatment. Always speak with your physician, pharmacist or other healthcare professional before taking any medication, supplement or adopting any treatment for a health problem.