Last Updated: 25 July 2019
When your child is suffering from viral fever – the first question you are sure to ask is
“How long will viral fever last?”
And here is the answer
What is the duration of fever in a child?
In children with good immunity the usual duration of viral fever is 3 – 4 days. In children with weaker immunity, viral fever may last longer and last persist for 8 – 10 days.
Children with good immunity may also sometimes suffer from viral fever for 8 – 10 days when there is a new virus in the air, to which they have never been exposed and therefore do not have immunity.
The duration of viral fever also depends on the age of the child.
How long does viral fever last in a toddler?
In infants and toddlers – viral fever lasts for longer than it does in older children. This is because – in toddlers the immunity is low. Toddlers are still developing immunity and it takes longer for their body to control the infection by the virus.
Why does viral fever last 3 – 4 days?
Our body fights viruses with the help of antibodies.
Each virus has to be fought with a different antibody. So just like there are millions of viruses – the body needs to produce millions of different types of antibodies.
These antibodies are produced by our body only after it comes in contact with the infecting virus. And it takes our body around 48 to 72 hours (2 – 3 days) to produce these antibodies.
The virus however has to be controlled as soon as it enters the body. The virus cannot be allowed to multiply and cause damage for the first 3 days before antibodies are produced.
So – in the first 3 days while the antibodies are still being designed and produced – the virus is controlled by raising the temperature of the body through fever and making it a very hot place in which the virus cannot survive and multiply. This is done by chemicals called cytokines and interleukins. These chemicals do not need to be virus specific since they are acting on the brain to raise the temperature of the body. They are not working on the virus at all.
In around 3-4 days when enough antibodies are produced to control the virus – the virus is neutralized or killed by the antibodies.
Because there is no more virus – there is no need to raise the temperature of the body to keep the virus in check. This is when the fever comes down.
Why does viral fever sometimes last longer than 3 – 4 days?
In younger children viral fever may last for longer than 3 – 4 days because they have a very small collection of antibodies because they have hardly encountered any viruses in their short lives.
Every time a virus attacks – they have to start producing antibodies to that virus one by one from scratch.
And this takes time.
Since every virus is a new virus for a toddler – and she/he has to begin to produce new antibodies against it., toddlers fall sick more often and they also have fever for longer.
You should also check – Best thermometer for kids
Why do some children recover faster from viral fever?
Toddlers who are breastfed fall sick less often and also have fever for shorter duration because they receive ready made antibodies from breast milk. And these antibodies help control the virus while the toddler’s body works to produce its own antibodies. Because antibodies (derived from breast milk) are present right from the time the virus enters the breastfed toddler’s body and can control the virus as soon as it enters the body – there is no need for cytokines and interleukins to raise the temperature of the body to protect it from viruses.
As children grow older they build a stock of more and more different types of antibodies. These antibodies kill the virus as soon as it enters the child’s body – so the child does not have the viral infection at all.
In case these antibodies are unable to kill the virus immediately they are still able to grow to large numbers much faster than in toddlers because by then the body has become skillful in producing antibodies. And so the duration of fever is much shorter.
Is it normal for fever to last 8 – 10 days?
In most children with good immunity – fever should reduce in 3 -4 days.
When fever lasts more than 3 – 4 days the following should be suspected
Secondary bacterial infection
In this case a bacteria has taken advantage of the child’s weak state and established itself and is now causing infection
Other infections like malaria
Malaria is a parasitic infection. There are many other kinds of infection that can cause fever and these should be suspected.
How long should you wait before you go to a doctor in viral fever?
It is best to go to a doctor on the very first day of fever for the following reasons –
The doctor can examine and be sure it is viral fever
When the doctor examines the child and is sure that it is a viral fever. She/he can confidently ask you to wait 3-4 days for the fever to come down on its own and will not start antibiotics.
The doctor has a baseline to assess the child from
When the doctor sees the child on the first day of fever – she/he has a baseline to assess the child from. In case the child develops a secondary bacterial infection after 4 days – the doctor is able to identify the changes quickly because she/he knows that these signs were not present on the first day. This helps the doctor to make a decision about starting or not starting an antibiotic. Otherwise unnecessary antibiotics may be started because secondary bacterial infection is suspected – even when it is actually just viral fever going on for longer than 4 days.
Also read Can a viral infection turn into a bacterial infection
The doctor can identify other infections like Malaria and Typhoid
In some cases the fever may not be due to a viral infection. It could be typhoid or malaria. It is impossible to differentiate viral fever from typhoid or malaria at home. However a doctor can easily identify the signs of diseases like typhoid or malaria. In these cases then medication can be started immediately without waiting for 3 – 4 days as is recommended for viral fever.
Also read Why wait before starting an antibiotic?
How to build immunity so that your child has a shorter duration of fever?
Breastfeed your child for as long as possible. Breast milk supplies ready-made antibodies that fight viruses and prevent fever. Continue breastfeeding when your child is sick.
Stop over-protecting your child
Allow your child to mingle with a lot of children while playing in bright sunshine and fresh air. This will allow your child to receive small doses of virus from other children. The fresh air will dilute the amount of virus coming to your child. And the sunlight will kill many of the viruses being passed around. As a result your child will get a small doses of viruses which will allow her/him to build antibodies without falling sick. These antibodies will protect her/him – when a real infection arrives and tries to attack.
Stop using soaps and cleaners that kill germs
The cells of the immune system are like soldiers of an army. They need to live among the enemy – in this case germs – to practice shooting their guns. When we kill all the germs around our children with disinfectants in floor cleaners and soaps – they lose practice and cannot fight the disease-causing virus when it attacks.
Fever is not always bad. It may be doing your child some good. Always check with your doctor before you give medicine to lower the fever.