Blood test results

High CRP (C-Reactive Protein)

CRP is made by your liver when there’s inflammation anywhere in the body. It rises within hours of an infection or injury and falls quickly as you get better. It tells you something is going on, not what or where.

Quick answer: Most labs call CRP under 5 mg/L normal. Mild rises of 5–10 are common with colds, smoking, extra weight or poor sleep. Most infections and inflammatory flares push it over 10, and results in the hundreds suggest bacterial infection or major inflammation. hs-CRP over 3 mg/L signals higher heart risk.

What the test measures

C-reactive protein is an acute-phase protein: the liver pumps it out within hours of infection, injury or an inflammatory flare, and levels can rise several hundred-fold. Because it falls within days once the cause settles, it’s useful for tracking whether treatment is working. It doesn’t show where the inflammation is.

Standard CRP vs hs-CRP. It’s the same protein. The high-sensitivity (hs-CRP) test measures very low levels accurately and is used to fine-tune heart disease risk in people who are otherwise well.

Typical adult ranges

What a high result usually means

Common causes:

Less common but important:

Very high results, in the hundreds, are more typical of bacterial infection, major injury or surgery than of viruses, but there’s overlap.

Symptoms

CRP causes no symptoms itself. What matters is the cause: fever, pain, swelling, cough, burning urine, joint stiffness, weight loss or night sweats.

What happens next

Get urgent help (000 in Australia, or your local emergency number) for a high CRP with signs of sepsis: confusion, fast breathing, shaking chills, mottled or very pale skin, or feeling the sickest you’ve ever felt. See a doctor the same day if you’re over 50 with a new headache, scalp tenderness, jaw pain when chewing or any change in vision: this can be giant cell arteritis, which can threaten sight. See your GP soon for a raised CRP with weight loss, night sweats or persistent pain.

Practise reading results. Play Panelysis, the daily blood-test puzzle: a fictional patient, a real-looking panel, three guesses. More in medical games.

Common questions

Can stress raise CRP?

A little. Long-term stress, depression and poor sleep are linked with slightly higher CRP, usually in the low single digits. Stress won’t explain a CRP of 30 or 100: that needs a proper look for infection or inflammation.

What CRP level is concerning?

It depends on how you are. Most infections and inflammatory flares push CRP over 10 mg/L, and results in the hundreds suggest bacterial infection or major inflammation. A mildly raised CRP in someone who feels well is often from a recent cold, smoking or extra weight.

Is a CRP of 7 bad?

It’s mildly raised and usually not worrying on its own. A recent cold, carrying extra weight, smoking, poor sleep or the contraceptive pill can all do it. If you feel well, your doctor may repeat it in a few weeks.

What’s the difference between CRP and hs-CRP?

They measure the same protein. Standard CRP looks for infection and inflammation; hs-CRP measures very low levels to help estimate heart disease risk in otherwise healthy people. Under 1 mg/L is lower risk, 1–3 average and over 3 higher.

Can CRP be high without an infection?

Yes. Injury, surgery, autoimmune conditions such as rheumatoid arthritis and polymyalgia rheumatica, gout, inflammatory bowel disease, some cancers and even obesity can raise CRP.

How fast does CRP go down?

Quickly. CRP falls within days once the cause starts to settle, which is why doctors use it to check whether treatment is working. A CRP that isn’t falling after a few days of treatment can be a sign the infection isn’t responding.

Evidence and more information

Updated 8 November 2026. General education, not personal medical advice. Reference ranges differ between laboratories, so use the range printed on your own report and talk to your GP about your result.

Related

maladywise.com/blood-tests/high-crp/