(NewsUSA) - Symptoms we all experience occasionally are rarely cause for concern. Yet even mild symptoms may be signs of serious illness.

Dr. J. Edward Hill, president of the American Medical Association and faculty member at the Family Medicine Residency Center in Tupelo, Miss., provides the following guidelines as to when common symptoms may be dangerous.

* Abdominal pain: The usual causes are gas, stress, viral or bacterial infections, such as food poisoning. But abdominal pain that lasts more than a day or two, causes severe cramps or is accompanied by nausea or vomiting could be appendicitis, gallbladder disease, gallstones, ulcers or stomach cancer. Call your doctor.

* Back pain: Call your doctor if pain from muscle pulls or spasms does not improve after a week. Pain accompanied by fever, tingling, numbness or shooting leg pains may indicate a spinal infection. See your doctor or go to an emergency room immediately.

* Chest pain: Physical overexertion is usually the reason for chest pain. Suspect a heart attack if the pain is accompanied by a pressing or crushing sensation, radiates from the chest to other parts of the body or is accompanied by heavy sweating, nausea or vomiting. Call 911.

* Constipation: Usual causes are insufficient fiber or water in the diet. Sudden constipation or alternating bouts of diarrhea and constipation may signal colon cancer. Call your doctor.

* Fatigue: Inadequate sleep and bad diet are typically to blame for tiredness. Significantly more fatigue than usual in the absence of any lifestyle changes could indicate heart disease. Schedule a checkup immediately.

* Headache: Fatigue or emotional stress can cause headaches. Yet anyone who gets them more than once a month or is incapacitated by a headache needs a complete medical workup immediately. Headaches that increase in frequency, are unusually severe, or are accompanied by other symptoms, such as nausea, slurred speech or vision changes, could be a sign of stroke, an infected or a ruptured brain blood vessel, meningitis or a brain tumor. Call 911.

* Heartburn: Common causes include indigestion - often from eating fatty or spicy foods - and gastroesophageal reflux disease. But if this condition occurs more than once a week, it can damage the esophagus and is linked to esophageal cancer. If you need antacids more than twice a week, see your doctor.