There’s a great scene in Woody Allen’s classic movie Hannah and Her Sisters. Woody’s character—a basically normal middle-aged man—asks his co-worker if she hears a strange ringing in her ears. She picks up the ringing telephone and says, “Yes, I hear it.” Later, he believes he has a “malignant melanoma” on his back, which turns out to be an ink spot on his shirt. Woody’s character has a classic case of Illness Anxiety Disorder, also known as Hypochondriasis.

We’ve probably all had a bit of unwarranted health panic at some point in our lives. Online sites like WebMD, which are supposed to help us self-diagnose our ailments, can sometimes take us down a rabbit hole that turns our undiagnosed (and totally temporary) swimmer’s ear into full-blown brain cancer.

Faced with such an overload of information—or faced with pure stubbornness or conviction in our healthy habits—it can be easy, even understandable, to simply ignore everything that seems wrong with our bodies. But that, obviously, is not the way to go. So, in the hopes of reducing panic but alerting us to legitimate symptoms that could signify a larger problem, here’s a little guide to what your body is really telling you.

Joint Pain

Your knee or wrist is tender. Maybe it’s swollen or red. Think back to the last couple days: Maybe you moved something heavy or did an inordinate amount of exercise. That could be the culprit. So could the normal process of aging. A red or swollen joint here and there is most likely nothing to worry about. However, according to the Blue Cross, if you notice a joint that is red, swollen and feels hot, you need to see a doctor soon. You may be suffering from a bacterial infection, gout or arthritis. The faster you act, the better the prognosis.

What to watch for: A trifecta of red, swollen, and hot-feeling (or inflamed) joints.

Vision

Unless you’re in Las Vegas or at a movie theater, you shouldn’t be seeing flashing or streaking lights, nor should you feel that you’re seeing the world through red-tinted sunglasses. Similarly, some eye conditions produce “floaters,” which are dark specks that seems to move across your line of sight like a dim meteor. All of these could be signals of one of several eye conditions that can lead to serious vision loss. Go see an opthamologist. (Note: These are not the occasional flickers that happen when you close your eyes for a moment—these are much more pronounced.)

What to watch for: Flashes, streaks of light, dark floaters, or a red filter that colors your normal sight.

Weight Loss

Most Americans could stand to lose a couple pounds (or a couple more than a couple). But we usually do that on purpose and with a lot of struggle. If you are shedding weight and can’t attribute it to a change in exercise or diet, or can't stop it, you may have a problem. To put some numbers on it: Doctors consider a loss of 5 percent of your body weight within a month, or 10 percent within 6-12 months, to be a possible symptom of certain kinds of cancer or an overactive thyroid.

What to watch for: Unexpected or inexplicable weight loss.

Shortness of Breath

Unless you have a previously diagnosed condition, such as emphysema or asthma, or you’ve just finished a vigorous work-out (good for you!), breath should flow freely in and out. But if you find yourself gasping for breath when resting, or your breath starts making a whistling sound, and if that breathlessness worsens when you recline, go see a doctor, but don't wait for an appointment with your cardiologist. This is an instance when a trip to the emergency room may be warranted. A host of cardiovascular problems, including heart attack and obstructive pulmonary diease, could be making themselves known.

What to watch for: Trouble breathing while resting.

Addiction

The physiological benefits of so-called “indulgences,” such as wine, chocolate and coffee, are well known. The caffeine in each has been shown to activate and help coordinate the central nervous system, and antioxidant properties in wine are helpful in flushing harmful free radicals from the system. The psychological benefits of dietary pleasure should also not be understated. But addiction to unhealthy food, drink and other substances is a very serious health problem facing millions of Americans. Addiction researchers are trying to teach us to pay attention to cravings as a sign of a dangerous addiction: daily, predictable cravings of anything from alcohol to sugary junk food are signs of an addition. As you are well aware, treatment programs exist, and they are often worth every penny and minute spent.

What to watch for: Daily triggers that make you crave unhealthy things.

A family friend of mine—a tough, hard-working man in his mid-sixties—once had shortness of breath. He saw his family practitioner, who told him to go to the emergency room immediately. On his way to the emergency room, he stopped at a diner for a breakfast of steak and eggs. When he got to the emergency room, his heart attack was well under way. The good doctors saved his life, but that little breakfast trip was the most dangerous diversion of his life.

My friend is the extreme opposite of Woody Allen’s hypochondriac, but neither one should be an example to live by. Cultivate healthy habits—exercise, diet and nutrition—and trust that passing fatigue and discomfort are just that: passing. But don’t miss or ignore the tell-tale signs that could improve the quality of your life or actually save it.