Physicians often have their own personal bugbears, ranging from the validity of alternative medicine to expensive private health checks.
These doctors reveal which treatments and tests they would personally avoid:
Dr Juliet Bressan, a Dublin GP who specialises in treating substance abuse, would never take sleeping tablets.
"They are very harmful and disturb your sleep. Sleeping tables cause a chemical sleep and, after two or three nights on them, you can experience this rebound phenomenon where you feel you can't sleep without them. It's not proper rest – just drug-induced sedation.
"They are not recommended for more than a few nights and definitely not for more than two weeks. After five or six nights, people complain of jitteriness and start waking up during the night. But they become quite dependent on sleeping tablets and feel completely awake without them.
"Patients are often in despair about sleep – they're tired, anxious and desperate for sleep. Doctors are usually very compassionate and want to help and it's very difficult to say no. They prescribe them for people with short-term difficulties, such as when someone close has just died.
"There is no harm in taking them if a doctor has prescribed them and you are taking them in a responsible way. What you want to avoid is people taking them without medical supervision.
"Elderly people are often prescribed sleeping tablets, but they might forget to take them or don't bother. So sleeping tablets are often passed around to families.
"Those people haven't had a proper consultation and end up addicted to them. I've seen so many people with an addiction to sleeping tablets.
"Often the cause of a sleep disturbance is a depressive illness or temporary anxiety disorder that you can manage in other ways, such as with counselling therapy. It does help to talk about sleep disturbances and see what the root cause is.
"If I have jet lag and can't sleep, I might take melatonin, which is a natural remedy. Unfortunately, we don't have it in Ireland, but you can get it in drug stores in America. It's very safe and very useful."
Dr Illona Duffy, a GP in Monaghan, would never mix alternative medicine with conventional treatments or use homeopathy.
"When you ask patients what medications they are on, they rarely mention alternative medication such as herbal tablets. My biggest bugbear is people presuming that they are completely safe. But they can interact with prescribed medication.
"There are lots of alternative practitioners who are excellent but others who have people with chronic illnesses paying a huge amount of money.
"'The cure' is very popular in these parts. I've had people come in with infected shingles because they've gone to see someone who spat on a tissue and rubbed it all over them. One local woman has a cure for verrucas that involves burying an apple in the back garden.
"In some cases, these 'cures' are harmless and patients benefit from a placebo effect. Some alternative therapies also work – acupuncture is one that has been tried and tested. But there is very little proof that homeopathy works.
"Before any medication goes on sale, it has to be tried and tested for years and years before it reaches the patient.
"Alternative therapies often go by word of mouth, with people using them because they know of someone it worked on.
"You always hear about the person it worked for, but never hear about when it goes wrong."
Dr Mel Bates, a GP in Dublin, would avoid full health screenings offered by private medical clinics.
"It bothers me when people spend a lot of money on full health checks. Some clinics charge €500 for them, and there is no medical evidence to support them. If there were sufficient scientific evidence, the HSE would have a duty to support it.
"The people who tend to get these health checks are the ones who are least likely to have any problems anyway. They are looking for reassurance because they have a vague concern about their health or have reached a certain age.
"There is nothing wrong with having your blood pressure checked, your cholesterol checked, deciding not to smoke, taking more exercise or losing weight – none of which costs money. If you suddenly become aware of your mortality or someone close to you has an illness and you become aware of your own health, seek the advice of a trusted medical adviser. The GP health checks wouldn't be as comprehensive, but they don't need to be, most of the time.
"I think part of the reason clinics provide these health checks is because there is a demand for it. During the Celtic Tiger, people would order a catalogue of tests like they were ordering a pizza.
"I would challenge anyone to show me how this is beneficial."
Dr Maurice Guéret, editor of the Irish Medical Directory and a GP in Dublin, would never get tested for a food intolerance.
"I would not undergo food tolerance testing unless the tests were specific, proven and supervised by a consultant in immunology, pathology, allergy or gastroenterology. Those specialists know the severe limitations of food allergy testing. Alas, others do not.
"It would be wise to discern the qualifications of those who say hundreds of food intolerances can be distinguished from a single blood sample.
"The consumer magazine Which? did its own research on food intolerance tests and found highly inconsistent results. It suggested that these tests 'play on people's phobias' and 'could potentially be risking people's health' by advising them to go on unbalanced diets based on fallacious tests.
"In the UK, the Science and Technology Committee at Westminster advised strongly that doctors should not offer them."
Dr Angie Brown, a cardiologist and the medical director of the Irish Heart Foundation, would never smoke.
"My opposition to smoking grew because of the needless damage it causes. I see patients debilitated with atherosclerosis (clogged arteries), which leads to life-threatening illnesses like heart attacks and stroke.
"I want my patients to live healthily as long as they can, and by not smoking they reduce their risk of heart attack, stroke, cancer and other illnesses that could shorten their life.
"Treatments have come a long way but there is always a risk of complications. Regardless of treatments, the reality is that one in two smokers die from smoking-related illness ."
These are the personal opinions of individual physicians. Anyone concerned about their health should consult their own doctor.