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Immunity and infection prevention

First signs of infection

The main article (“Fever: when to seek urgent care”) explains how infection is recognised in general. This topic lists, one by one, the first and often subtle signs in each part of the body.

Last updated: ~1 min read
A silhouette with glowing dots.
Figure 1.First signs appear in different parts of the body.

01Short answer

With weak immunity, the first signs of infection can be subtle. The main one is fever or chills, but other signals matter too: sudden weakness or just “not feeling right”; sores, white patches or pain on swallowing; cough, breathlessness or chest pain; burning when passing urine; diarrhoea or tummy pain; redness, swelling or tender spots on the skin; redness or discharge around a catheter; pain around the back passage. People taking steroids and older people may have no fever at all, and confusion or severe weakness may be the only sign.

02Simple explanation

Fever and chills: the main sign.

Subtle signals: weakness, sores, cough.

There may be no fever.

03Scientific explanation

Hidden signs: in neutropenia inflammation is weak, so there is little redness or pus; pain may be the only sign.

Chills: shivering after a catheter flush can point to a catheter infection.

04What happens in the body?

A map of signs

The first signals can appear in the mouth, chest, skin, catheter site and abdomen.

Thermometer and notebook

Measuring and writing down your temperature helps you notice early.

A thermometer on a notebook.
Figure 2.Measure and write down your temperature.

The catheter site

Redness or pain around a catheter is an important signal.

A ring of redness at a catheter exit.
Figure 3.Redness at the catheter site.

05Recognising it early

Four steps.

Feeling — Feeling unwell.1FeelingFeeling unwell.
Measuring — Temperature.2MeasuringTemperature.
Looking — Check your body.3LookingCheck your body.
Calling — Tell your team.4CallingTell your team.

06Body area and first sign

AreaFirst sign
GeneralFever, chills, weakness
MouthSores, white patches, painful swallowing
LungsCough, breathlessness
Urinary tractBurning, passing urine often
Skin and catheterRedness, swelling, discharge, pain

07Key terms

Chills
Feeling cold before or with a fever.
Weakness
A lack of strength.
Dysuria
Burning when passing urine.
Catheter exit site
Where the catheter leaves the skin.
Confusion
Unclear thinking.

08Key points

  • Fever is the main sign.
  • Watch for subtle signals too.
  • There may be no fever.
  • Check the catheter site.
  • Write down your temperature.
  • If in doubt, call.

09Frequently asked questions

At what temperature should I call?

Your team sets this threshold; get it in writing.

No fever, but I feel bad; what should I do?

Call anyway; with weak immunity that is enough.

I shivered after a catheter flush; does it matter?

Yes, report it at once.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. At what temperature should I call?

  2. No fever, but I feel bad; what should I do?

  3. I shivered after a catheter flush; does it matter?

My questions

12Sources

  1. National Cancer Institute (NCI). Infection and Neutropenia during Cancer Treatment
  2. MedlinePlus (U.S. National Library of Medicine). Fever
  3. American Cancer Society. Infections in People with Cancer
  4. Centers for Disease Control and Prevention (CDC). Flu and Cancer
  5. American Cancer Society. Vaccinations During Cancer Treatment
  6. UK Health Security Agency (Green Book). Immunisation of individuals with underlying medical conditions: the green book, chapter 7
  7. UK Health Security Agency (Green Book). Contraindications and special considerations: the green book, chapter 6
  8. NHS. Vaccinations
  9. Centers for Disease Control and Prevention (CDC). Preventing Respiratory Illnesses
  10. Centers for Disease Control and Prevention (CDC). Masks and Respiratory Viruses Prevention
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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