By Corrie Pikul


These are the myths and misconceptions that drive doctors crazy (and could affect your health). Let's clear them up -- once and for all.


1. Makeup with SPF is just as good as sunscreen.


Women tend to be (justifiably) wary of caking on makeup, but this means they rarely put on the amount of sunscreen-enhanced foundation, tinted-moisturizer or lipstick required to protect their skin from the sun, explains Justin Piasecki, MD, a plastic surgeon and the founder of the Skin Cancer Center in Gig Harbor, Washington. They also neglect to reapply the products every two to three hours, which is the amount of time Piasecki says it takes for any sunscreen to wear or rub off, and for the sun's UV rays to deactivate its protective ability. This is why makeup with SPF can be 14 times less effective than sunscreen. Piasecki says that at least one-third of skin cancers occur above the neck, so he recommends wearing sunscreen with UVA/UVB protection under your makeup every day and carrying a travel-size sunscreen in your purse so you can reapply it when you're outside.


2. Drinking milk will make your runny nose worse.


"I have patients who swear that milk makes them produce more mucous," says Jennifer Collins, MD, an assistant professor and a physician specializing in allergy, asthma and immunology at the New York Eye and Ear Infirmary. However, she hasn't been able to find any good research to support that -- and neither have other doctors. In fact, when Australian researchers went so far as to collect and weigh the nasal secretions of 60 volunteers inoculated with the common-cold virus, they found no association between milk intake and mucous production. Scientists think that drinking milk may remind some people of the consistency of mucous or may coat their throat in a way that makes them think they're feeling more phlegm. Collins notes that drinking milk fortified with vitamin D can help boost your energy, spur cell growth and help keep your immune system working optimally. Those who are firmly anti-milk (for whatever reason) can get their vitamin D from fish like swordfish, salmon and tuna, or from fortified orange juice or cereal.


3. A sprinkle of talcum powder a day will keep moisture away.


Baby powder (or scented talcum powder) can be easily inhaled into the lungs and, worse, has been linked to cancer. Harvard researchers recently found that postmenopausal women who use talcum powder in their genital area just once a week increase their risk of developing endometrial cancer by 24 percent. Another Harvard study found a strong link between talcum powder use and ovarian cancer (it can increase the risk of developing the cancer by up to 40 percent). In general, family doctors have stopped recommending that women use talcum powder to absorb wetness. Stick to preventative measures like wearing breathable cotton underwear and rinsing regularly with warm water.


4. Topical antibiotics should be your go-to for minor cuts and wounds.


Many of us automatically reach for neomycin (one of the active ingredients in ointments like Neosporin) whenever we have a cut or scrape. But constantly exposing the skin to neomycin can lead to an allergic reaction over time, says Reid Blackwelder, MD, a professor of family medicine at East Tennessee State University who sits on the board of directors of the American Academy of Family Physicians. "People will then use the ointment and assume the resulting redness comes from the wound, when it's actually the neomycin affecting their skin." Some studies have also suggested the widespread use of OTC ointments with neomycin, polymyxin or bacitracin may contribute to the development of resistant bacteria, says Blackwelder. For minor wounds like hangnails, shaving cuts and paring-knife nicks, he suggests using soap and water to clean and disinfect the area. If you think the area is infected, talk to your doctor.


5. Vaccines can cause developmental disorders in children.


This remains a hotly debated issue, despite being debunked in multiple large studies. And now the United Kingdom is dealing with a serious outbreak of measles partly as a result of the large number of children who were not inoculated against the disease during the MMR vaccine scare of the early 2000s. Measles, mumps and rubella are still relatively uncommon in the United States, but there has been an uptick in recent years. The United Kingdom has launched a massive, expensive catch-up campaign to quickly vaccinate as many children as possible, and our Centers for Disease Control and Prevention continues to stress the importance of making sure that you and the children in your life are vaccinated.


6. Eating a lot of carrots can save your failing vision.


Vitamin A is essential for good vision -- no one's refuting that -- but you only need a small amount. One half-cup of raw carrots will provide you with 184 percent of the recommended daily value. An excessive amount of beta carotene, the compound in carrots that's converted to vitamin A, can not only make your skin turn orange, but studies show it has also been associated with an increased risk of lung cancer in some people. So enjoy the crudité, but if you worry that your eyesight is failing, make an appointment with an optometrist or an eye doctor.


7. You can catch a cold from not bundling up in cold weather.


Not necessarily, Collins says. Viruses do tend to be more active in cold weather, but a down coat won’t protect you if you’re run-down and haven’t been taking care of yourself. She says that you can catch a cold from staying inside in cold weather, especially if there are lots of other people around. Here's why: When it gets chilly outside, we tend to crowd indoors and crank up the heat. Collins explains that this causes the mucous membranes inside our nose to become dry and cracked, making us even more vulnerable to germs being passed around by family members, friends and coworkers. Collins adds that regularly exercising outdoors has a protective effect on our immunity, even when the weather outside is frightful. Just be sure to wear the right layers: Dress as if it's 10 degrees warmer than it is (you'll feel chilly to start, and comfortable after about five to ten minutes of moderate intensity).


As a reminder, always consult your doctor for medical advice and treatment before starting any program.


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    We do get them</a> on our cheeks, says <a href="www.ArtofDermatology.com" target="_blank">Jessica Krant, MD</a>, a board-certified dermatologist and assistant clinical professor at <a href="http://www.downstate.edu/" target="_hplink">SUNY Downstate Medical Center</a>. Goose bumps, or cutis anserine, occur where we have hair -- pretty much everywhere except for our palms and soles of feet, Krant says. She breaks down the process: Each hair follicle contains a microscopic muscle called arrectores pilorum that contracts in response to the sensation of cold, or the feelings of fear or excitement. The reason most of us, especially women, don't notice goose bumps on our face is because the peach fuzz there is usually fine and short, and our facial skin muscles are less robust than those in our arms and legs. Krant adds that if you find goose-pimply bumps on any part of your body that don't seem to be affected by fear or temperature, you might have <a href="http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002433/" target="_hplink">keratosis pilaris</a>, an eczema-like condition caused by inflamed follicles.




  • 'Does Being Overweight Mean You'll Get Pregnant Easily?'


    We don't see many images of fertility goddesses as skinny stick figures. And it's true that <a href="http://www.asrm.org/Abnormal_Body_Weight/" target="_blank">underweight women make a form of estrogen that can be too weak for successful conception</a>, according to the American Society for Reproductive Medicine (ASRM). But while obese women often have an overabundance of estrogen, this can affect their cycle to the point that they stop ovulating. Excess weight can influence fertility in other ways, too: A 2007 Dutch study of more than 3,000 couples (without any known ovulation problems) found that women with a body mass index of 30 or higher <a href="http://humrep.oxfordjournals.org/content/23/2/324.full" target="_blank">had significantly lower probability of becoming pregnant</a>, when compared with women with BMIs of between 21 and 29. This is why the ASRM stresses the importance of maintaining a healthy weight when trying to conceive. By the way, having full hips won't even provide an advantage during childbirth: "It's the front-to-back dimension that creates the tightest squeeze," discovered <a href="http://www.nathanaeljohnson.org/all-natural/" target="_blank">Nathanael Johnson</a> while exploring the science and history of childbirth (among other biological processes) for his book <a href="http://www.powells.com/biblio/62-9781605290744-0" target="_blank">All Natural</a>. So an average-weight woman has the best chance of getting pregnant naturally and giving birth more easily.




  • 'Why Don't People Who Take Nitroglycerin For Their Heart Blow Themselves Up?'


    This query usually exposes a childhood fascination with Road Runner cartoons, says <a href="http://www.med.nyu.edu/biosketch/wlg2" target="_blank">Billy Goldberg, MD</a>, a New York emergency room physician and the co-author (with Mark Leyner) of <a href="http://www.whydomenhavenipples.com/" target="_hplink">two</a> <a href="http://www.randomhouse.com/book/101276/why-do-men-fall-asleep-after-sex-by-mark-leyner-and-billy-goldberg-md" target="_hplink">books</a> about health trivia ("the stuff everyone wants to know, but that doctors aren't taught in medical school," Goldberg says). For those who've forgotten: <a href="http://www.youtube.com/watch?v=u9bC_3cNH34" target="_blank">Wile E. Coyote would blow himself up</a> with explosive nitroglycerin -- the same substance used in heart medication. In the commonly prescribed pill form, <a href="http://www.nlm.nih.gov/medlineplus/druginfo/meds/a601086.html" target="_blank">nitroglycerin</a> helps increase blood flow to oxygen-deprived areas of the heart by dilating blood vessels. The medicinal dose of nitroglycerin in heart medication is infinitesimal compared with the amount in a stick of dynamite, explains Goldberg in <em><a href="http://www.amazon.com/Why-Men-Fall-Asleep-After/dp/0307345971" target="_blank">Why Do Men Fall Asleep After Sex?</a></em>. It's also highly diluted for safe handling.




  • 'Can Sunshine Trigger A Sneezing Fit?'


    Goldberg says this is one of his favorite questions -- mostly because he assumed it was too ridiculous to be true. While writing <em><a href="http://www.amazon.com/Nipples-Hundreds-Questions-Doctor-Martini/dp/1400082315" target="_blank">Why Do Men Have Nipples?</a></em>, he and Leyner pored over medical textbooks and studies to find out that some people have a strange reaction to blazing sunlight that causes them to sneeze uncontrollably. This is due to something called the photic sneeze reflex -- also known as autosomal dominant compelling helio-ophthalmic outburst, or ACHOO. A 2005 study of six Spanish families showed that <a href="http://www.ncbi.nlm.nih.gov/pubmed/16007510" target="_blank">there are usually two to three "achoo"s per episode of ACHOO</a>. This reflex is relatively under-studied and not completely understood, says Goldberg, but it is thought to have something to do with an accidental crossing of nerve signals.




  • 'Why Does It Feel So Hot Out When It's 90 Degrees If Our Bodies Are 98.6?'


    This question comes up all the time, says Goldberg (most likely during the sweltering East Coast summers). The answer is found in the human body's way of regulating temperature. We're constantly producing heat as we burn calories and exert energy, says Goldberg, and the heat needs to escape. He explains that it's easier to release pent-up heat when the temperatures outside are moderate or cool. When the temps soar, the body increases blood flow to the skin to help the heat escape through sweat. The hotter it gets, the more sweat and energy the body needs to exert, and the harder it ends up working. As a result, you feel like you're burning up.




  • 'If You're Stranded On A Desert Island Should You Drink Ocean Water Or, Um, Your Own 'Water'?'


    This is definitely one of the more far-fetched questions Goldberg has been asked in his 20-plus years as an emergency room doctor and <a href="http://www.med.nyu.edu/biosketch/wlg2" target="_blank">assistant professor of emergency medicine at New York University</a>. But the answer underscores the importance of staying hydrated at all times. Our drink of choice would have been seawater. But Goldberg informs us that we have it wrong: Seawater is three times as concentrated as human blood, and to process it, the body would need to excrete the excess salt through the kidneys as urine. As your body worked to flush out the salt, you'd lose precious fluids and become even more dehydrated. Before long, your muscles would atrophy, your heart would pound out of rhythm, and you'd eventually die of dehydration. He says it's probably safer to drink urine than seawater, but you'll probably be too dehydrated to make enough to quench your thirst.




  • 'Can Pins And Needles In Your Feet Cause You To Become Paralyzed?'


    Goldberg says he's seen many people end up in the ER because they've failed to respond to that weird prickly feeling, perhaps because they've been knocked out by alcohol, sleeping pills or a punch in the face. He explains that when you've been kneeling for too long (or doing something else that puts pressure on your leg), the arteries in that area can become compressed, preventing them from providing tissues and nerves with oxygen and glucose. This also blocks nerve pathways, causing some nerves to stop firing and others to go off like a 4th of July fireworks finale. When the brain receives these signals, it interprets them as that uncomfortable sensation of pins and needles. Prolonged pressure on the arteries can indeed lead to temporary or even permanent nerve damage, so it's important to respond to the feeling as soon as you notice it.