Hematologist
CION Cancer Clinics
How to check a temperature correctly at home | CION Cancer Clinics
Use a digital thermometer in the mouth or armpit, after resting and without a hot or cold drink first, and wait for the beep. If the reading is 38 degrees Celsius (100.4 degrees Fahrenheit) or higher and the person is on blood cancer treatment, go to hospital the same day. This page shows how to measure properly, which thermometer to trust, and what a home reading cannot tell you. At CION Cancer Clinics, our haematology team supports patients and families through treatment, cost questions and life at home.
BP
Medically reviewed by Dr. Basudev PokhrelConsultant Haematologist · last reviewed September 2026, next review due September 2027
17+specialists on panel
15,000+patients treated
35+centres across Telangana & AP
4.8★ / 800+Google rating
On this page
- What temperature reading should worry you?
- How do you take a temperature the right way?
- Which thermometer should you use at home?
- What do families get wrong about fever at home?
- What should you do with the number you see?
- What can a home reading not tell you?
- Common questions about checking temperature at home
The short answer
What temperature reading should worry you?
If you or your parent is having treatment for a blood cancer, a reading of 38 degrees Celsius (100.4 degrees Fahrenheit) or higher means you go to hospital the same day. Use a digital thermometer, wait until you have not eaten or had a hot drink for a while, and write down the number and the time.
Why a thermometer matters more than a hand on the forehead
Treatment for leukaemia, lymphoma and myeloma often lowers the white cells that fight infection. When those cells are low, an infection can spread through the body within hours. A fever may be the first and only sign. A hand on the forehead cannot tell 37.8 from 38.2 degrees, and that small gap decides whether you leave for hospital now or wait.
What counts as normal
A normal body temperature sits around 37 degrees Celsius. It varies a little through the day and from person to person. So a single reading matters less than knowing what is usual for you, which is why it helps to check once or twice a day on ordinary days too.
Low readings matter as well
Some people, especially older people or those on steroids, do not run a fever even when an infection is serious. A reading that is unusually low for you, with shivering, confusion or feeling suddenly very unwell, needs the same urgent care.
Your own treating team may give you a different number to act on. If they have, follow theirs.
!
When to leave for hospital now
If the reading is 38 degrees or higher, or you have shivering, fast breathing, confusion or feel suddenly very unwell even with a normal reading, go to the nearest emergency department the same day. Call 108 if you cannot travel safely. Say that the person is having treatment for a blood cancer and their counts may be low. Do not wait to see if it settles by morning.
Not sure whether this applies to you?
Ask an oncologistStep by step
How do you take a temperature the right way?
Wait and sit quietly
Do not measure straight after a bath, exercise, a hot or cold drink, or a meal. Sit down and rest for a while first. A cup of hot tea just before can push a mouth reading up, and a cold drink can pull it down.
Place it properly
For the mouth, put the tip under the tongue towards the back and close your lips around it. For the armpit, dry the skin, put the tip in the deepest part and hold the arm firmly against the side.
Wait for the beep
Keep still and do not talk until the thermometer beeps. Taking it out early gives a reading lower than the truth, which is the most common mistake families make.
If unsure, check again
If the number looks odd, wait a few minutes and repeat it the same way. If either reading reaches 38 degrees, act on it. Do not keep checking until you get a lower number.
Write it down
Note the reading, the time, the method, and any fever medicine taken in the last few hours. Show this to the doctor.
Choosing a thermometer
Which thermometer should you use at home?
A simple digital thermometer from any pharmacy is enough. Buy it before treatment starts, not on the night you need it.
Digital, in the mouth
Cheap, easy to read and reliable when used correctly. Most teams suggest it for adults.
Not suited to
- A sore or ulcerated mouth
- Someone breathing through the mouth
- Young children or a confused adult
Digital, in the armpit
Gentle and useful when the mouth is sore. It usually reads a little lower than the mouth, so do not dismiss a reading close to the line. Use the same method each time so you can compare.
Ear or forehead
Quick, but the reading shifts with how the device is aimed, with ear wax, and with sweat or a fan. If one of these gives a high or borderline number, recheck with a digital thermometer. Do not wait long doing it.
Mercury glass and fever strips
Glass mercury thermometers break and are hard to read in poor light. Forehead strips only show roughly warm or not warm. Neither is reliable enough when the decision is whether to go to hospital tonight.
Commonly believed
What do families get wrong about fever at home?
"He does not feel hot, so there is no fever."
Touch is not a measurement. Cold hands feel warm skin as hot, and warm hands miss a fever entirely. When counts may be low, only a thermometer reading should decide what you do next.
"Give a tablet first and see if it comes down."
A fever medicine can lower the number for a few hours while the infection keeps spreading. It hides the warning without treating the cause. Ask your treating team in advance what they want you to do, and always tell the hospital about anything already taken.
"It is only a little over, we will go in the morning."
With low white cells, the hours between the first fever and antibiotics matter a great deal. Night-time is not a reason to wait.
"No fever means no infection."
Older people and anyone on steroids may not run a fever at all. Shivering, confusion, dizziness, fast breathing or suddenly feeling very unwell are reasons to go even with a normal reading.
Leave a number, we will call you
One field. No form to fill in, and no charge for the call.
Reading to action
What should you do with the number you see?
What you see
What to do
38 degrees Celsius (100.4 degrees Fahrenheit) or higher, once
Go to the nearest emergency department today. Call 108 if needed.
Normal reading, but shivering, confusion or feeling very unwell
Go the same day. Do not wait for a fever to appear.
Slightly raised, below 38 degrees, and feeling well
Rest, recheck in a while, and call your treating team for advice.
Normal reading and feeling well
Carry on with your usual daily checks and write it down.
Being straight with you
What can a home reading not tell you?
A thermometer tells you when to act. It cannot tell you what is causing the fever, how low the counts are, or how serious an infection is. Only a blood test and an examination in hospital can answer that. A normal reading also does not prove all is well.
Who this guidance does not fit
This page is written for adults having treatment for a blood cancer or a blood disorder that lowers the counts. Babies and young children are measured differently, and their doctors use different rules. If your child is on treatment, follow the written plan from their own team.
Make a plan before you need it
At your next visit, ask three questions. What number should make us come in? Which hospital should we go to at night? Should we give any fever medicine before we leave? Write the answers on a card with the thermometer. Keep a bag ready with the treatment summary and a list of medicines.
This page cannot replace advice from the team treating you. If what they told you differs from this page, their advice comes first.Questions we are asked
Common questions about checking temperature at home
How often should I check the temperature during treatment?
Many teams suggest checking at the same times each day, such as morning and evening, and any time you feel hot, cold, shivery or unwell. Your own team may ask for more checks in the days when counts are expected to be lowest. Ask them for a routine that suits your treatment, and keep a simple written record.
Is an armpit reading accurate enough?
It can be, if the skin is dry, the tip sits deep in the armpit and the arm is held firmly until the beep. It usually reads a little lower than the mouth. So treat a borderline armpit reading seriously rather than adding or subtracting a number yourself. If in doubt, go to hospital.
The reading was 38 degrees once, then lower. Do we still go?
Yes. Most blood cancer teams ask you to act on a single reading at or above 38 degrees when counts may be low. A lower second reading does not cancel the first, especially if any fever medicine was taken. Go the same day and tell the doctor both numbers and the times.
Can I give paracetamol for the fever?
Ask your treating team this question before a fever happens, because the answer depends on your treatment. What matters is that a tablet can lower the reading and hide an infection. Never let a lower number after a tablet stop you going to hospital, and always tell the doctor what was given and when.
Does the time of day change the reading?
A little. Body temperature is usually lower in the early morning and higher in the late afternoon and evening. Eating, hot drinks, a bath, heavy blankets and exercise also nudge it up for a while. This is why you wait and rest before checking, and why an evening reading at 38 degrees still counts.
My father feels unwell but his temperature is normal. What now?
Take it seriously. Older people and those on steroids may not run a fever even with a serious infection. Shivering, confusion, dizziness, fast breathing, a new cough or passing much less urine are all reasons to go to the emergency department today. Tell them he is on treatment for a blood cancer.
We live far from Hyderabad. Which hospital should we go to?
Go to the nearest emergency department you can reach quickly, not the one furthest away that you know best. Losing hours on the road is the bigger risk. Carry the treatment summary and the recent blood report. Ask the doctor there to contact your treating team once antibiotics have been started.
Should the thermometer be cleaned or shared?
Keep one thermometer only for the person on treatment, if you can. Wipe the tip with soap and water or an alcohol swab before and after each use, and let it dry. Replace the battery when the display fades, because a weak battery can give readings you cannot trust.
Your Haematologist
Meet CION's haematologist. One specialist for your blood report and your plan.
Dr. Basudev Pokhrel reviews blood counts, transfusion needs and blood disorders, and works with the CION tumour board on blood cancers.
Want a specific doctor for your case? Mention them when booking.
Book Free ConsultationBook an appointment with our specialist
Share your name and number — we'll call you back within 30 minutes to schedule your consultation.
Patient stories
Hear it from people we have treated
Every story is a video, in the patient's own words. Nothing here is a written testimonial.
Sources
- NHS — High temperature (fever) in adults
- NICE — Neutropenic sepsis: prevention and management in people with cancer (CG151)
- American Cancer Society — Low blood counts
- Macmillan Cancer Support — Side effects and symptoms
- National Health Mission — National Health Mission
This page is general information, not a prescription. Do not change or stop any treatment based on what you read here. If anything is worrying you, contact your own treating team — or call our helpline and we will help you reach the right specialist.
Keep reading
Related pages
Neutropenic Fever: The Single Most Important EmergencyWhat happens once you reach hospital with a feverThe One-Hour Antibiotic RuleWhy the hours after a fever matter so muchWhat a low white cell count and ANC meanHow to read the white cell count on your reportWhich Days After Treatment Are RiskiestWhen to check the temperature most carefullyCounts, Fever and Infection in HaematologyThe full guide to low counts and infection
Talk to us
Not sure what number should bring you in?
Call the helpline. CION's haematology team will talk you through a fever plan for your treatment. One helpline serves every CION centre.