HAVING SEX CAN CAUSE A HEART ATTACK IN MEN

How wrong is this? Fairly. The risk is hugely exaggerated by the familiar portrayals of men in books, films and dramas gasping their last in flagrante.

What are the facts? Research shows that the chances of a 50-year-old non-smoking male suffering a heart attack is about one in a million in any hour. Having sex increases these odds to two in a million, but doubling a barely existent risk means that risk is still negligible.

Any related myths? That sex is a form of exercise. In fact, it equates only to climbing two flights of stairs.

HIGH BLOOD PRESSURE CAUSES HEADACHES

How wrong is this? Very. An astronomically high blood pressure might cause a headache, but this is rare.

What are the facts? High blood pressure (hypertension) usually has no symptoms at all. It's not a disease, it's a risk factor, so it is treated to reduce your chances of a future stroke or heart attack, not too make you feel better.

Any related myths? That high blood pressure causes dizziness. No, dizzyness is a side-effect of the treatment.

DIABETICS CRAVE SUGAR

How wrong is this? Fairly. Diabetics do have to alter their sugar intake and they sometimes require an urgent sugar fix if their blood glucose is too low. So concluding that craving sugar equals diabetes is understandable but wrong.

What are the facts? Diabetes isn't caused by excess sugar, it's simply that the diabetic body has problems handling it.

Any related myths? That diabetics need to buy special, low-sugar versions of food and drink. They don't - a simple healthy diet will suffice.

WOMEN NEED TO EXAMINE THEIR BREASTS

How wrong is this? Very.

What are the facts? Research shows that routine self-examination does no good in terms of breast cancer outcomes because it isn't sensitive enough to detect important lumps. In fact, it can actually cause harm. How? By subjecting self-examiners to increased levels of anxiety.

Any related myths? There is an exact parallel with routine self-examination of testicles in males - another discredited activity that continues to receive publicity because it sounds like a good idea.

DIETS CUT CHOLESTEROL

How wrong is this? Fairly. Doctors rarely suggest diet alone if your cholesterol really needs lowering.

What are the facts? A healthy diet's a good idea. But if you want lower cholesterol, you'll probably be disappointed. Because, even in trials, the best that's achieved is a 10 per cent reduction. Most cholesterol is made by your liver, with your dietary intake contributing little. Cholesterol is usually treated with statins.

Any related myths? That a high cholesterol is a cause for panic - it's simply a risk factor, like high blood pressure, for future problems.

HEADACHES ALONE CAN BE A SIGN OF A BRAIN TUMOUR

How wrong is this? Totally.

What are the facts? The stats alone may be ease your headache. After all, your GP sees this symptom daily, but encounters a brain tumour only a few times in his entire career. Nasties of this sort almost always produce other symptoms - fits, personality change or unsteadiness.

Any related myths? That a scan is a good idea. The chances of turning up an irrelevant but worrying abnormality are fairly high.

YOU SHOULDN'T MIX ANTIBIOTICS AND ALCOHOL

How wrong is this? Totally, with the exception of the antibiotic metronidazole.

What are the facts? Any interaction of alcohol with virtually all antibiotics is nonexistent, or so small as to be irrelevant. Metronidazole, an antibiotic used for a variety of infections, is the exception to this rule. When mixed with even small amounts of booze, it causes vomiting.

Any related myths? That you should always finish your course of antibiotics. It usually makes little difference.

YOUR TIREDNESS MAY BE CAUSED BY ANAEMIA

How wrong is this? Fairly.

What are the facts? Tiredness is common and, in the absence of other symptoms, is usually caused by lifestyle issues such as stress and lack of exercise. Mild anaemia caused by iron deficiency is common, too, particularly in women. As tiredness often prompts a blood test, it's common for anaemia to be revealed, and assumed wrongly to be the cause.

Any related myths? That tiredness will be solved by vitamins - though the chemist might tell you otherwise.

FLU JABS GIVE YOU FLU

How wrong is this? Totally. You might suffer a sore arm or, at most, a slight fever.

What are the facts? The vaccine does not contain live germs and so cannot cause flu. But, as it's given in autumn, peak snuffle period, many patients will pick up a virus around the time of their jab. This they misinterpret as flu, which they link to the jab.

Any related myths? The idea that if you are healthy, the flu jab isn't necessary. In fact, it's recommended to all over-65s, even if they're fit and well.

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