5 Medical Myths Debunked

Does cold weather really make you sick? Is it true you lose weight on exercise alone? NewYork-Presbyterian experts separate fact from fiction about commonly held health beliefs.

Drink at least eight glasses of water a day. Reading in low light can hurt your eyes. Cold weather makes you sick.

Whether passed down from generation to generation or circulated over the internet and social media, medical myths like these are just that … myths.

Here, NewYork-Presbyterian experts put some common myths and misconceptions into context.

MYTH 1: Cold Weather Makes You Sick

Eyeing the dropping temps with trepidation since they typically trigger a cold or flu? Turns out, Mother Nature isn’t to blame.

“While it is true that people do get sick more often during the colder months of the year, cold weather itself does not cause illness,” says Dr. Judy Tung, chair, department of medicine at NewYork-Presbyterian Lower Manhattan Hospital and associate professor of clinical medicine at Weill Cornell Medicine. “The seasonality of certain viruses, like influenza, as well as more time spent indoors when it’s cold out, encourages viral spread. The majority of upper respiratory infections are caused by viruses, and exposure to these germs and the ability of your immune system to fight is what makes you sick.”

MYTH 2: You Can Lose Weight With Exercise Alone

If you’re looking to shed the extra pounds you gained this year, here’s a reality check: Solely logging miles on the treadmill probably won’t do it.

“Exercise is good for your heart, muscles, bones, mental health, and for longevity,” says Dr. Rekha B. Kumar, assistant professor of medicine, division of the Endocrinology/Comprehensive Weight Control Center at NewYork-Presbyterian/Weill Cornell Medical Center and medical director of the American Board of Obesity Medicine. “That being said, trials looking at the effect of exercise on weight loss show insignificant weight loss with the intervention of exercise alone without caloric restriction. On average, a person can lose about six pounds from exercising without controlling diet. The combination of a calorie-restricted diet plus exercise is the key to long-term weight control. The time when exercise is more important in controlling weight is once a person has lost a substantial amount of weight; studies show that doing approximately 250–300 minutes of exercise per week can help people keep off weight they have lost.”

MYTH 3: A Woman Cannot Get Pregnant During Her Period

In a typical 28-day cycle, a woman ovulates on day 14 (on average), a process that lasts about 12 to 48 hours. But that doesn’t mean conception can’t occur outside that window.

“Theoretically, if she is bleeding for days 1–7, then it makes sense to think that she will not be able to get pregnant if she has sex while she is still bleeding,” says Dr. Alexis Melnick, assistant attending obstetrician and gynecologist at NewYork-Presbyterian/Weill Cornell Medical Center and assistant professor of reproductive medicine and obstetrics and gynecology at Weill Cornell Medicine. “However, this is not always the case. Not all cycles are the same length, so even if a woman gets a period once per month, she may have a 25-day cycle one month, a 27-day cycle the next, and a 26-day the month after — and may actually ovulate earlier than day 14. Furthermore, sperm can live for three to five days in the female genital tract. So even if ovulation happens after bleeding stops, if the sperm are still present, conception can occur.”

What’s more, Dr. Melnick says, “as women get older, menstrual cycles typically shorten and ovulation can happen within the first few days of a cycle, even while bleeding is still occurring. Lastly, many women will have mid-cycle bleeding, often around the time of ovulation, which can be mistaken for a period. Bottom line, if a woman does not want to get pregnant, she needs to be using contraception throughout all days of her cycle.”

MYTH 4: Men Are More Susceptible to Heart Disease

Heart disease is the No. 1 cause of death for both men and women in the United States. The difference is that women are affected later in life than men, according to Dr. Nisha Jhalani, attending cardiologist at NewYork-Presbyterian/Columbia University Irving Medical Center and assistant professor of medicine at Columbia University College of Physicians and Surgeons.

Before women hit menopause, on average in their early 50s, estrogen is protective against heart disease. But estrogen levels drop after menopause. That’s why postmenopausal women should see their doctor regularly to discuss their cardiovascular risk, Dr. Jhalani says.

“Heart disease kills more women each year than every form of cancer combined,” she says. “Women are actually more likely than men to die of their heart attack and are also more likely to have a silent heart attack or have atypical symptoms of a heart attack. This, in turn, makes them more likely to be misdiagnosed when presenting to the emergency room and are treated less aggressively with procedures and medications. After menopause, the rate of heart disease is the same or greater for women as it is in men.”

The good news? While “90 percent of all women have at least one risk factor for heart disease and/or stroke,” she continues, “many of these risk factors are modifiable. Therefore early detection and treatment of these risk factors can prevent the vast majority of heart attacks.”

MYTH 5: You Shouldn’t Use Expired Medications

If you have a headache, but that bottle of ibuprofen expired six months ago, it turns out you can safely use it to treat your ailment.

That’s because “drug manufacturers are mandated by a 1979 law to stamp expiration dates on their bottles of medications,” says Dr. Tung. “This date represents the date at which the manufacturer will guarantee the full potency of the drug. However, the actual shelf life of the medication may be much longer.

“A large study conducted by the FDA for the Department of Defense found that many medications are good for up to an average of five years and many even up to 15 years,” says Dr. Tung. “Notable exceptions to this include certain medications such as antibiotics or insulin. A good general rule of thumb is to adhere to the expiration date for medications where even a small difference in the dose matters. For the rest, it is likely safe for even up to a few years to take expired medications.”

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