Worried about your risk of developing a serious disease? It's hard not to when you read the latest health headlines.

Consider just a few of the most recent ones: Common pain relievers raise your risk for heart attacks. Sitting too much may make you more likely to develop cancer. Drinking just one soda per day boosts your chance of diabetes.

What these stories often don't explain is that these risks may be overstated or even completely misrepresented, and they don't apply to everyone equally.

The promise of online risk calculators is that they can help you look beyond the latest headlines and figure out your personal risk for diseases such as cancer and heart disease. The reality, however, is that they usually can give you only a ballpark guess about your level of risk. 

Here's what you need to know before you try one out.

Using Online Risk Calculators

With online risk calculators such as the American Diabetes Association’s Type 2 Diabetes Risk Test, you plug in information such as your age, health history, and health habits, and receive estimates of your risk factors for developing a disease.

But in 2015, a study in the Annals of Internal Medicine found that four risk assessment tools, including one developed by the American Heart Association and American College of Cardiology, overstated the risk of events such as heart attacks in men and women. A fifth overestimated those risks in men but underestimated them in women.

“No risk calculator is perfect,” says Marvin M. Lipman, M.D., Consumer Reports’ chief medical adviser. For one thing, not all calculators take the same risk factors into consideration, and some look at fewer than others. “The more factors involved, the more accurate the risk assessment is,” Lipman says.

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Furthermore, some calculators may not ask for enough detail.

For example, the Fracture Risk Assessment Tool (FRAX) asks about the use of corticosteroid drugs—a risk factor for bone breaks—but it considers only average use and forces doctors to use their clinical judgment for those with high or low use. In fact, a team of international researchers recently reported that the risk assessment tool may overestimate the number of women who should take drugs to prevent osteoporosis. Some calculators ask only for yes or no answers instead of detailed responses that might yield more useful information.

Risk calculators are only as good as the information you enter. If you put in your blood pressure level incorrectly, for example, the calculator’s risk assessment will be off.

Despite the drawbacks, risk calculators “can give you a very good idea of where you stand relative to other people your age,” Lipman says. You and your physician can then discuss your results and decide what, if anything, to do to lower your risk.

Don't like your odds? See below for some reliable ways to reduce your risk for the most common diseases and conditions.

This is an example of part of an online health risk calculator.

Reducing Your Health Risks

Though nothing is guaranteed to protect you, institutions such as the National Institutes of Health and the Institute of Medicine say you can lower your risk for many diseases.

Even those who carry a genetic predisposition for a disease may benefit. “If family members developed a cancer in their 40s, reducing risk factors might prevent it or shift it toward older ages,” says Joy Larsen Haidle, a cancer expert for and past president of the National Society of Genetic Counselors. Here, evidence-based risk-­reducing strategies for five health concerns:

Cardiovascular disease. Don’t smoke; if you do, quit. Control your blood pressure, maintain a proper weight, follow a healthy diet to keep your cholesterol within a normal range, drink in moderation, and exercise regularly. Those steps will lower your risk for type 2 diabetes, high blood pressure, and high cholesterol, which all increase your risk for heart disease and stroke.

A daily baby aspirin (81 milligrams) or a regular aspirin (325 milligrams) every other day may reduce the risk of a second heart attack in men ages 45 to 79 and cut the risk of ischemic stroke in women ages 55 to 79 (ask your doctor whether taking aspirin is right for you). People whose cholesterol and blood pressure don’t respond to lifestyle changes may need prescription drugs.

Breast cancer. Limit alcohol, stay at a healthy weight, and if you are prescribed hormone therapy, use it for the shortest possible time. Exercising for more than 4 hours per week may reduce risk, too.

Prescription tamoxifen or raloxifene may lower breast cancer risk in postmenopausal women; tamoxifen may do the same in high-risk premenopausal women.

Prescription aromatase inhibitors may cut the likelihood of breast cancer in high-risk, postmenopausal women and prevent a recurrence in breast-cancer survivors. Women who carry the BRCA1 or BRCA2 gene mutation may want to discuss prophylactic mastectomy and/or oophorectomy (ovary removal) with their physicians.

Type 2 diabetes. Lose excess weight, and strive to be physically active—even walking five days a week for 30 minutes in each outing can reduce risk or slow the development of the disease.

The medication metformin helps lower elevated blood glucose levels in people with the condition and may delay development of the disease in some people with prediabetes.

Colorectal cancer. Exercise regularly, talk with your doctor about whether you should take a daily aspirin, and limit alcohol. (Three or more daily drinks ups risk.) Having colon polyps larger than 1 centimeter removed during colonoscopy has also been shown to make a difference.

Hip fracture. If you’re 65 or older, exercise regularly to strengthen muscles and improve balance, which may prevent falls.

The government recommends at least 150 minutes per week of ­moderate- or 75 minutes of vigorous-intensity aerobic activity. You should also do muscle strengthening exercises at least twice weekly. People who can’t reach those totals should be as active as possible.

Because insufficient calcium may make you more susceptible to fractures, our experts advise 1,000 milligrams of daily calcium for women ages 19 to 50 and 1,200 milligrams after that; men should strive for 1,000 milligrams up to age 70 and 1,200 milligrams after that.

Also, avoid or minimize smoking and alcohol, which contribute to bone loss.

If you’re at high risk for osteoporosis, your doctor may recommend exercise, calcium, and vitamin D, or, possibly, bisphosphonate medication such as alendronate (Fosamax and generic) to keep bones from thinning too much. And if you need to use corticosteroids long term, talk with your doctor about bone-protective strategies.