How acute inflammation turns chronic

Inflammation may have started as the solution—for example, as a way to rid the body of a dangerous invader—but if it doesn’t turn off when it should, it instead can become the problem. The body’s immune response may keep inflammation going, long after the threat has cleared. Acute inflammation has now transitioned to chronic inflammation.

Chronic inflammation can develop in any of several ways. One possibility is that the threat remains because the body can’t rid itself of the offending substance, be it an infectious organism, an irritant, or a chemical toxin. The immune system is pretty good at eliminating invaders, but sometimes pathogens resist even our best defenses and hide out in tissues, provoking the inflammatory response again and again.

Another possible scenario is that the immune system goes into "threat mode" when no true threat exists. In an autoimmune disorder, the immune system seems to become overly sensitized to the body’s own healthy cells and tissue. It reacts against the joints, intestines, or other organs and tissues as if they were dangerous. As the inflammatory response continues, it damages the body instead of healing it.

Unhealthful lifestyle choices, too, can cause ongoing inflammation. Smoking, being sedentary, or eating a diet high in processed foods and refined carbohydrates can contribute to chronic inflammation. This ongoing inflammation increases the risk of many diseases—including heart disease, stroke, diabetes, cancer, and chronic obstructive pulmonary disease.

Signs and symptoms of chronic inflammation

The signs of chronic inflammation are not as obvious as those of acute inflammation. No sharp twinge of pain as when you cut yourself, no swelling or redness will you see to alert you to a problem. Chronic inflammation can be widespread or more localized to specific areas of the body. Some of the symptoms associated with chronic inflammation include:

• fatigue and lack of energy
• depression, anxiety
• muscle aches and joint pain
• constipation, diarrhea, and other gastrointestinal complaints
• changes in weight or appetite
• headaches
• a "fuzzy" mental state (brain fog).

For additional advice about ways to reduce inflammation, check out  Fighting Inflammation , a Special Health Report from Harvard Medical School.

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