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Ask a Doctor is a series of physician-authored columns offering insights and advice on common health topics. It is not a substitute for seeking medical care.
Fever is one of the most common reasons I see parents bring their kids to the emergency department – especially as cold and flu season ramps up. It’s also riddled with a lot of misunderstanding. While there are definitely times when a child with fever should be checked by a doctor, parents are often surprised when I tell them fever is actually a good thing because it’s the body’s way of fighting off infection.
Here are some reminders about what a fever is, why kids get fevers so often and when to seek medical attention. (And bonus: Much of this advice applies to adults too.)
What is a fever?
A fever is defined as a body temperature of 38 C (100.4 F) or higher
The most common symptoms of fever include chills, body aches and fatigue. Someone with a fever often feels hot to touch and can start sweating as the fever breaks and temperature cycles back to normal.
Children develop fevers more often than adults because their immune systems are still developing and constantly encountering new viruses and bacteria. Add in close contact, imperfect hygiene and lots of exposure and you’ve got a recipe for frequent fevers.
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A fever itself isn’t an illness, but part of the body’s immune response to an infection. This increase in temperature actually helps the immune system work more efficiently by slowing down the growth of bacteria and viruses. Fevers act as a defence mechanism for the body and are not dangerous in and of themselves.
Some children may experience febrile seizures, and while this can be very scary for parents, they do not damage the brain or cause long-term harm.
It’s important to remember that for both kids and adults, the actual number does not indicate the type or severity of the infection. A simple cold can cause a fever above 40 C and something serious like pneumonia can cause a fever of 38.5 C.
The best method for taking a temperature depends on age. For babies under two years old, a rectal temperature is most accurate. For toddlers, the armpit or ear methods are good choices, and for kids over age 5 or 6 (who can reliably hold a thermometer in their mouth), using an oral thermometer is recommended. Forehead strips and touchless scanners are okay for a quick screen, but not always reliable.
When is a fever cause for concern?
Most fevers are harmless and caused by viral infections that will resolve on their own, but there are exceptions. Babies younger than three months are at higher risk for serious infections, and their immune systems aren’t as strong. Any fever in that age group should be checked by a doctor.
The same goes for anyone who is immunocompromised, whether from chemotherapy, chronic illness or medications that suppress the immune system (such as those for autoimmune diseases). These individuals can’t mount the same immune defences, so a fever could signal a much more serious infection that could spread more quickly than usual if left untreated.
Another important factor in determining how serious a fever could be is vaccination status. Children who have received their routine vaccinations (against diseases such as Hib - Haemophilus influenzae type B - or pneumococcal disease) are less likely to develop a fever caused by a serious bacterial infection. This means when we see fully immunized individuals in the ER, we can usually assess the cause of fever by taking a medical history and conducting a physical exam.
However, for underimmunized or unimmunized children, we are more likely to investigate further with tests such as bloodwork, urine cultures or maybe even a lumbar puncture to determine if an invasive bacterial illness is the culprit.
Vaccines don’t just prevent disease, they also reduce the number of invasive tests and hospital admissions kids might otherwise need when they get a fever.
When to see a doctor
Here is when I tell parents to have their child checked:
- Any fever in a baby younger than three months old.
- Fever in someone who is immunocompromised or unimmunized.
- Fever lasting more than four or five days, as this could indicate a potentially more serious cause.
- Trouble breathing, stiff neck, severe headache, persistent vomiting or rash, which could indicate meningitis.
- A child who is unusually sleepy, very irritable or not drinking fluids, which could indicate dehydration.
- Any time your gut tells you something’s off. Parents know their kids best. If it doesn’t feel right, it’s worth getting checked.
Treating fever at home
While a fever can cause discomfort, it is not necessary to suppress it because fever is not dangerous. I always advise parents to treat the person, not the number.
This means if your child has a fever but is functioning well, able to drink fluids and is resting comfortably, you don’t need to give anti-fever medication. However, if your child has fatigue or poor fluid intake, it’s time to treat the fever to make them more comfortable.
Acetaminophen (Tylenol) or ibuprofen (Advil/Motrin) can be used to treat a fever, depending on the child’s age. Ibuprofen should not be given to babies younger than six months. And ASA (acetylsalicylic acid) or aspirin should never be given to children because of the risk of Reye’s syndrome.
Don’t forget non-medication measures: keeping your child hydrated with low-sugar electrolyte-rich fluids like Pedialyte or broth, dressing them lightly and letting them rest.
A fever almost always indicates a contagious infection, so your child should stay home to prevent the spread until symptoms improve and the fever has been gone for at least 24 hours without any anti-fever medications.
Dr. Shazma Mithani is an emergency physician working with adult and pediatric patients in Edmonton. Dr. Mithani is actively involved with the Canadian Medical Association, Alberta Medical Association and Sexual Assault Centre of Edmonton. She is also co-host of The Doc Talk Podcast.