Unexplained Weight Loss
A 5% weight loss over the course of a month or a 10% weight loss over six months to a year shouldn't be ignored. It could be a sign of a number of health issues, including overactive thyroid, depression, liver disease or cancer. Seeing a doctor could make a difference in the effectiveness of your treatment.
A persistent, low-grade fever of more than 100.4 degrees should be cause for seeing a doctor if it lasts over a week. It could be a sign of an infection, such as endocarditis, which affects the inner lining of the heart. Some cancers also can cause prolonged fevers.
Shortness of Breath
Shortness of breath after climbing a flight of stairs is somewhat normal. You should be concerned, however, if you find yourself gasping for air when you're lying down--a possible sign of congestive heart failure. Other causes could include asthma, anxiety, panic attacks or a blood clot in the lungs.
Unexplained Changes in Bowel Habits
A change in your bowel habits could be a sign of a bacterial or viral infection, an inflammatory bowel disease or colon cancer. Consider seeing a doctor if you have severe diarrhea for more than two days, mild diarrhea lasting a week, constipation for more than two weeks or bloody diarrhea.
Short-term Loss of Vision, Speaking, Movement or Control
Immediate care is crucial for stroke victims. Watch out for sudden weakness or numbness of the face, arm or leg on one side of the body, sudden dimness, blurring or vision loss, and a loss of speech, including trouble talking or understanding speech. Other symptoms include a sudden or severe headache and sudden dizziness or a loss of balance.
Flashes of Light
Suddenly experiencing a sensation of flashing lights could be a sign of retinal detachment, when the retina separates from a thin layer of blood vessels called the choroid. Without prompt surgical attention, retinal detachment can cause permanent vision loss.
Feeling Full After Eating Very Little
If you're feeling full quicker than normal after eating or have persistent nausea or vomiting for a week, see a doctor. You could have a gastrointestinal disorder. The symptoms also could be caused by pancreatic, stomach or ovarian cancer.
Hot, Red or Swollen Joints
Swelling, especially during the summer, is common. It should be cause for concern, however, if it's affecting the joint and accompanied by a red appearance, heat and pain. These symptoms may point to an infection, which needs immediate treatment to prevent the spread of bacteria.
Mental Status Changes
Changes in your behavior or the way you think could be reason to see a doctor. These symptoms could be caused by an infection, head injury, stroke, low blood sugar or medications you're taking. Watch out for confused thinking, disorientation, sudden aggressive behavior and hallucinations.
New or More Severe Headaches
Don't ignore a sudden and severe headache, particularly if you are over 50. Headaches along with a fever, stiff neck, rash, mental confusion, seizure, vision changes, weakness, numbness, speaking problems, scalp tenderness or pain with chewing are also cause for concern. Causes may include stroke, blood vessel inflammation, meningitis, brain tumor, aneurysm or brain bleeding following head trauma.
(In Pictures: Medical Symptoms You Shouldn't Ignore http://www.forbes.com/2007/07/23/health-symptoms-doctor-forbeslife-cx_avd_0724health_slide_2.html?thisSpeed=15000 )