In short
Sepsis is the body's runaway response to an infection, and it can progress from 'feeling unwell' to organ failure within a day. Knowing the handful of warning signs — and acting on them fast — is what changes the outcome.
Emergency if: Infection plus confusion, fast breathing, mottled or bluish skin, very little urine, or a temperature that is very high or unusually low — call emergency services now.
On your report
WBC / Total Leukocyte Count, CRP, Procalcitonin, Lactate +2 more
On this page
01
What Sepsis Actually Is
Sepsis isn't a particular germ. It's what happens when the immune system's response to an infection stops being targeted and starts damaging the body's own tissues and organs. Blood vessels leak, blood pressure falls, and organs such as the kidneys, lungs and brain begin to fail from lack of oxygen.
Any infection can be the trigger — pneumonia, a urinary infection, an infected wound, a bout of gastroenteritis, even a dental abscess. Most infections never go this way, which is exactly why sepsis is so often missed early: the first hours can look like an ordinary illness getting a bit worse.
02
The Signs That Should Make You Act
Sepsis tends to announce itself as a cluster: confusion or unusual drowsiness, breathing fast or feeling short of breath, a racing heartbeat, skin that is mottled, pale or bluish, shivering with fever or — importantly — a temperature that is unusually low, and passing far less urine than normal.
A useful rule from emergency medicine is 'the sickest they've ever been'. If someone with an infection is deteriorating quickly, seems not themselves, or describes a feeling of impending doom, that pattern matters more than any single number. In babies and older adults the picture is often quieter — feeding poorly, floppy, cold hands and feet, or simply 'not right'.
03
What the Blood Tests Show
In hospital, sepsis is confirmed and tracked with blood work rather than a single test. The white cell count is often very high (or, in overwhelming infection, abnormally low), CRP and procalcitonin rise as markers of bacterial inflammation, and lactate climbs as tissues become starved of oxygen — a rising lactate is one of the strongest signals that treatment needs to be escalated.
Creatinine and urea track how the kidneys are coping, bilirubin and liver enzymes show whether the liver is affected, and platelets often fall as clotting becomes disordered. Blood cultures are drawn before antibiotics wherever possible, so the exact organism can be identified and the treatment narrowed later.
04
Why the First Hour Matters
Treatment is time-critical: intravenous antibiotics, fluids to support blood pressure, oxygen, and finding and controlling the source of infection. International guidelines aim to start antibiotics within the first hour of recognition, because every hour of delay measurably raises the risk of death.
Most people who are treated early recover fully, though tiredness, poor concentration and low mood for weeks afterwards — sometimes called post-sepsis syndrome — are common and worth mentioning to a doctor rather than pushing through alone.
05
Lowering Your Risk
Keeping vaccinations current (influenza, pneumococcal, COVID-19), cleaning and covering wounds, and completing prescribed antibiotic courses all reduce the chance of an infection escalating. People with diabetes, kidney disease, cancer treatment, a removed spleen or who are over 65 are at higher risk and should have a lower threshold for seeking care when an infection isn't settling.
If you or someone you're caring for has an infection and develops confusion, fast breathing, mottled skin or is not passing urine, treat it as an emergency. Ask directly: 'could this be sepsis?' — it prompts the right checks.
When to act
Emergency — act now
Infection plus confusion, fast breathing, mottled or bluish skin, very little urine, or a temperature that is very high or unusually low — call emergency services now.
Same-day — call promptly
An infection that is clearly getting worse despite treatment, shivering fits, or a fever in someone over 65, pregnant, on chemotherapy or with diabetes.
Routine — see a doctor
Lingering tiredness, brain fog or low mood in the weeks after a serious infection — book a review; post-sepsis recovery is real and supportable.
Values mentioned in this story
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Sources
- Sepsis — MedlinePlusmedlineplus.gov
- Sepsis — NHSnhs.uk
- Sepsis — WHO fact sheetwho.int
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