Inflammation shows up in two very different ways depending on whether it’s acute (short-term) or chronic (long-lasting), and recognizing which type you’re dealing with is the first step. Acute inflammation is usually obvious: you can see and feel it at the site of an injury or infection. Chronic, low-grade inflammation is far sneakier, producing vague symptoms that overlap with dozens of other conditions. Both types can be confirmed with specific blood or stool tests if your symptoms warrant investigation.
Signs of Acute Inflammation
Acute inflammation produces five hallmark signs that are hard to miss. Redness and warmth happen because blood flow surges to the affected area, bringing body-core-temperature blood into cooler tissue like skin. Swelling results from fluid leaking out of blood vessels and pooling in the surrounding tissue. Pain occurs because the inflammatory process releases chemicals that directly stimulate nerve endings. And if the area is inflamed enough, you lose some ability to use it normally, whether that’s a swollen ankle you can’t walk on or a sore throat that makes swallowing difficult.
This kind of inflammation is generally a good thing. It means your immune system detected a problem and is actively working on it. It typically resolves within days to a couple of weeks as the tissue heals. If it doesn’t resolve, or if you keep getting inflammation in the same spot, that’s when it starts crossing into chronic territory.
Symptoms of Chronic Inflammation
Chronic inflammation doesn’t announce itself the way a swollen knee does. Instead, it produces a constellation of symptoms that individually seem minor but together paint a picture of an immune system stuck in low-level overdrive. Common signs include persistent fatigue that sleep doesn’t fix, joint pain or stiffness (especially in the morning), digestive problems like diarrhea, constipation, or acid reflux, and frequent infections that suggest your immune system is stretched thin.
You might also notice unexplained weight changes in either direction, recurring low-grade fevers, abdominal or chest pain, mouth sores, skin rashes, or insomnia. Depression, anxiety, and other mood shifts are also linked to chronic inflammation, likely because the same immune signaling molecules that drive inflammation throughout the body also affect brain chemistry.
The challenge is that none of these symptoms are unique to inflammation. Fatigue alone could point to a hundred different causes. What makes chronic inflammation more likely is when several of these symptoms cluster together and persist for weeks or months without a clear explanation.
Your Skin Can Be a Window
Certain skin conditions are more than cosmetic problems. They’re visible evidence of systemic inflammation happening throughout your body. Psoriasis is a prime example: the severity of skin plaques correlates directly with elevated blood markers of inflammation, and people with severe psoriasis have measurably higher levels of the same inflammatory proteins that drive heart disease risk.
Hidradenitis suppurativa, which causes painful lumps under the skin (typically in the armpits or groin), also tracks closely with systemic inflammation markers. Even acne severity correlates with inflammatory blood markers, particularly in deep, cystic forms. Eczema (atopic dermatitis) involves a different branch of the immune system but still elevates general inflammation markers in more severe cases.
If you have a chronic skin condition that flares and remits, it’s worth understanding that what you see on the surface often reflects what’s happening internally.
Blood Tests That Measure Inflammation
When symptoms are vague, blood tests offer concrete numbers. The two most commonly ordered are high-sensitivity C-reactive protein (hs-CRP) and the erythrocyte sedimentation rate, usually called a sed rate or ESR.
High-Sensitivity CRP
CRP is a protein your liver produces in response to inflammation. The high-sensitivity version of the test can detect even small elevations. Results below 2.0 mg/L are considered lower risk, while 2.0 mg/L or above signals higher risk, particularly for cardiovascular disease. One limitation: CRP levels fluctuate considerably from day to day, with a biological variability of around 30%. A single reading can be thrown off by a recent cold, a tough workout, or poor sleep. Your doctor may want to retest if the result seems inconsistent with your overall picture.
CRP levels also run about 40% higher in women than in men on average, which means the same number can mean different things depending on your sex.
Sed Rate (ESR)
This test measures how quickly red blood cells settle to the bottom of a tube over one hour. Inflammation causes certain proteins to increase in your blood, making red blood cells clump together and sink faster. Normal ranges depend on age and sex:
- Males under 50: less than 15 mm/hr
- Males over 50: less than 20 mm/hr
- Females under 50: less than 20 mm/hr
- Females over 50: less than 30 mm/hr
Like CRP, an elevated sed rate doesn’t tell you where the inflammation is or what’s causing it. It simply confirms that something inflammatory is going on. Both tests are typically used as starting points to guide further investigation.
Newer Testing: GlycA
A newer blood marker called GlycA measures the sugar molecules attached to a group of inflammatory proteins in the blood. It has a few advantages over CRP: its biological variability is only about 5% compared to CRP’s 30%, meaning it gives more consistent results from one draw to the next. It also shows smaller differences between men and women (less than 10%, versus CRP’s 40% gap). In research studies, GlycA remained significantly associated with mortality risk even after adjusting for other cardiovascular risk factors, while CRP lost its statistical significance under the same adjustments. That said, GlycA testing isn’t yet widely available or standardized for routine clinical use.
Testing for Gut-Specific Inflammation
If your symptoms are primarily digestive, like persistent diarrhea, cramping, or bloody stool, a standard blood test may not give the full picture. A calprotectin stool test measures a specific protein released by white blood cells in your intestinal lining. Normal or low levels generally rule out inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis. High levels confirm that your intestines are actively inflamed, with higher numbers indicating more severe inflammation.
This test is particularly useful for distinguishing between IBD and irritable bowel syndrome (IBS), which can produce similar symptoms but doesn’t involve the same kind of tissue inflammation. Somewhat elevated levels can also appear with celiac disease, certain bacterial infections, colorectal cancer, or regular use of anti-inflammatory painkillers like ibuprofen.
Body Composition as a Clue
Carrying excess weight, particularly around your midsection, is one of the strongest predictors of chronic inflammation. Fat tissue stored around your organs (visceral fat) actively produces inflammatory signaling molecules. In a large population study, each 13.5 cm increase in waist circumference was associated with a 0.52 mg/L increase in CRP, enough to shift someone from a lower-risk category into a higher one.
This is one reason waist measurement matters more than weight alone. Two people at the same body weight can have very different inflammation profiles depending on where their fat is distributed. If your waist circumference has been increasing over time, that alone raises the probability that chronic low-grade inflammation is part of your metabolic picture, even before symptoms appear.
Putting the Pieces Together
No single symptom or test result confirms chronic inflammation on its own. The clearest signal comes from combining what you feel with what the numbers show. Persistent fatigue, joint stiffness, digestive issues, and skin flare-ups happening alongside an elevated CRP or sed rate tells a much more convincing story than any one of those factors in isolation. If you suspect inflammation, tracking your symptoms over a few weeks before requesting bloodwork gives both you and your doctor a clearer starting point for figuring out what’s driving it.