Like red-light warnings on the dashboard, the human body sends out a flare when something's awry. Chest pain, shortness of breath, dizziness -- those are some familiar medical symptoms.
But other problems can creep up on you, too -- aches and pains, lumps and bumps. When are they important, when are they not?
In his book, Your Body's Red Light Warning Signals, Neil Shulman, MD, provides a head-to-toe owner's manual for the human body. His book lists hundreds of medical symptoms that could mean life or death, or serious disability.
Shulman, a professor of internal medicine at Emory University School of Medicine in Atlanta, has authored numerous medical books and scientific papers.
It's serious stuff, stuff he likens to "terrorists inside our bodies," he tells WebMD. The symptoms are "killing way too many people. There's tremendous suffering and horrible death which could be avoided, but people don't know that something's wrong."
In fact, it happens all the time, a symptom is missed -- and it leads to a tragic ending. Or it's caught just in time, and a life is saved. Quite literally, it's that dramatic, Shulman tells WebMD.
Here are "six flags" -- six medical symptoms -- you should keep in mind:
1. If you have unexplained weight loss and/or loss of appetite, you may have a serious underlying medical illness.
"If you're on a diet, you're expecting this to happen. But if you're eating the same way -- and now have to adjust your belt a few notches tighter -- you could have a serious problem," Shulman says.
"With ovarian cancer, the opposite is true," he says. "Fluid builds in the abdomen, and women think they are gaining weight. But if you have been at the same weight range for years, and doing nothing different, see a doctor."
2. Slurred speech, paralysis, weakness, tingling, burning pains, numbness, and confusion are signs of a stroke, and you should get to an appropriate emergency center immediately. Early treatment may prevent permanent damage to the brain or even save your life.
Slurred speech can often go unnoticed, says Shulman. However, you might have a blood clot in a blood vessel going to the brain or bleeding in a blood vessel.
3. Black, tarry stools may indicate a hemorrhage from an ulcer of the stomach or the intestine. It is important to stop the bleeding and to rule out cancer as a cause.
What you eat changes the color of stools. But black, tarry stools mean there may be bleeding higher in the intestine, says Shulman. It could be a sign of a bleeding ulcer or cancer in the intestine.
4. A headache accompanied by a stiff neck and fever is an indicator of a serious infection called meningitis.
In fact, if you can't put your chin on your chest, that's a sign you may have bacterial meningitis, says Shulman. You need antibiotics immediately to kill the bacteria before it infects and scars the brain.
5. A sudden, agonizing headache, more severe than any you have felt before, could mean you are bleeding in the brain. Go to an emergency room immediately.
A brain aneurysm is rare, but it can happen -- even in people under 40. "It can be very disastrous if it's not treated," says Shulman. If you have a severe, crushing headache, you may have an aneurysm, which is a blood-filled pouch bulging out from a weak spot in the wall of a brain artery. If treated before it bursts, it could save your life.
6. For women: Vaginal bleeding after menopause is a waning sign of possible cancer.
Some women are in denial when they discover postmenopausal bleeding. "Others think it's a little cut, or something in their urine," says Shulman. But bleeding after menopause is a sign of uterine cancer, which is treatable if caught early.
6. For men: A lump in your testicle with or without a small lump in the groin could be serious. Testicular cancer is more commonly found in testicles that did not naturally descend from the abdomen to the scrotum.
Guys, when you take a shower, check yourself, says Shulman. "That doesn't mean you have to do it every day, but once in awhile. It's so simple, simpler than washing your hair. It becomes an automatic thing, then it's easier to remember. If you know what 'normal' feels like, then you'll know when it feels abnormal."
'Squeaky Wheel' Works
It's an old, old saying: The squeaky wheel gets the grease. But it's vitally important in medicine, says Shulman. If you know something's not right with your body -- if you've got that severe, crushing headache, but doctors aren't taking it seriously -- stand up for yourself.
Tell doctors you know it could be a problem -- "I want you to rule this out," you should say. If they balk, here's your line: "I want you to write on the chart that you refused to do proper tests." Doctors are human; they get tired and distracted. It helps to get extreme, to get their attention, says Shulman.
"Sometimes you have to make a scene," he tells WebMD. "The one person most likely to be concerned about whether you live or not is you. You have the greatest empathy for yourself."
All adults -- from senior year of high school and up -- should be familiar with standard medical symptoms, to help them preserve their good health.
SOURCES: Your Body's Red Light Warning Signals. Neil Shulman, MD, professor of internal medicine, Emory University School of Medicine, Atlanta.