They're not very pleasant and not good for the economy either, according to a recent survey by Benylin investigating the impact of coughs and colds on Irish people. It found that employers here are losing in the region of 30m a year as a result of sick days taken due to coughs and colds. Few of us are lucky enough to escape the season unscathed but take some comfort in the fact that there are steps you can take to protect yourself.

The terms 'cold' and 'flu' tend to be bandied around but there are significant differences. A cold is an inconvenience but if you've caught a strain of flu you won't be able to work or probably even get out of bed because of the aches and pains that it causes, according to Dr Bill Tormey, consultant in Beaumont hospital. Colds are caused by hundreds of different types of viruses, which is why we can get them several times a year. They usually target the nose and upper part of the respiratory tract; in other words they're usually confined about the neck and don't cause a fever.

Flu, on the other hand, is more serious because it infects the whole of the respiratory system and there are associated complications such as bacterial pneumonia. Symptoms for flus (which you're more likely to catch between the months of November and February) include headache, fever, muscle and joint pain, as well as sensitivity to light, nausea and vomiting.

There are three major types with influenza A and influenza B causing the majority of infections. A third type, influenza C, is rarely reported as a cause of human illness.

According to Dr Tormey, people develop antibodies to specific strains of the flu if they're re-exposed to it, so they won't get the same virus twice. When the flu mutates and a new strain develops, as happens every year, they can catch it again. If you want to see how much flu actually is going around at present, the Health Protection Surveillance Centre publishes a weekly report online, amalgamated from the information submitted by GPs around the country. It can be found under 'Publications' in the Influenza section of Topics A-Z on its website, www. ndsc. ie. In the meantime, here's what you can do to try and keep those bugs at bay.

Eat Right Working, going to school, using public transport or going to the shop . . . whatever we're doing, we're in constant contact with people, which makes it very difficult to avoid the hundreds of cold viruses doing the rounds. The weaker your immune system, the greater susceptibility you have to infection so eating to boost your body's defences is key. The most important thing is to have an overall balanced diet, says Margot Brennan of the Irish Dietetic Institute (www. indi. ie). Now is a good time to take a good close look at what you are eating and make sure your dietary choices are good ones.

"The other most important nutrient when it comes to boosting our immunity overall is iron, and particularly so for women. A third of Irish women are not taking enough iron in their diet every day, " she says. "If you are below par, you will pick up bugs and cold and flus, probably on a more regular basis."

Symptoms include constant tiredness and breathlessness if it's advanced. It's a condition that many women who are in the early stages of pregnancy will relate to, when the body has to accommodate more blood for the baby and it brings about a dilution effect so it has similar symptoms. "If you're not eating red meat at least twice a week, you're probably not getting enough iron, " Brennan says. "Women need one and a half times the iron of men and red meat really is the best source for women."

Plant sources, meanwhile, include tofu, kidney beans, prunes and fortified breakfast serials. Vitamin C is important for the absorption of iron but contrary to the widely held belief, there's actually no proof that it prevents or cures a common cold. Adequate intake of Vitamin C does play an important role in fighting infection however, and for colds extra Vitamin C might have a mild histamine effect, perhaps shortening the length of the cold and making the symptoms less severe.

However, according to Brennan, scientific evidence doesn't justify taking large doses of Vitamin C on a regular basis to boost immunity. In fact, you can develop something called rebound scurvy (the disease caused by lack of Vitamin C) if you're somebody who swallows two grams of Vitamin C a day and then stops taking it. But it is something that you need to take on a daily basis, and for adults that is 60mg a day. If you are already eating your five portions of fruit and vegetables a day, you should be getting sufficient amounts of it, but smokers need to consume additional quantities. Other key minerals to boost an immune system are zinc (rich sources include red meat and fish, milk, cheese and wholegrain cereals) and selenium (found in Brazil and cashew nuts, fish and shellfish).

Think about a supplement According to Brennan, in the ideal world if you take the food pyramid as a yardstick you should be getting a good overall balance in your diet. "But life's not perfect and people are busy and that's not always happening, " she says. The rule of thumb is if you are going to use a supplement, buy a reputable brand and only buy a product that has 100% of your RDA (recommended daily allowance). In relation to supplements, such as echinacea, she says that there is no solid evidence as to how it may help colds and flus if it does. Most mainstream dietary experts do not believe that pills like these can reduce your chances of infections but it hasn't stopped a thriving vitamin and mineral industry or many million supplement devotees from championing them.

Alison Smyth, a homeopath and manager of Nelson's Homeopathic Dispensary, Duke St, Dublin 2 (01 6790451) sees increased business at this time of year with customers looking for alternative ways of staying bug-free. Echinacea, said to calm the immune system, is the top seller but ginseng and garlic extract are also popular choices. Another increasingly popular preventative strategy is taking probiotic drinks and yoghurts. A daily dose of probiotics, such as acidophilus or lactobacillus, has been shown to boost the gut, which contains most of the immune cells in the body, thus helping to prevent infections.

Wash your hands The number one cause of harbouring, spreading and getting the common cold is touching everyday objects with contaminated hands. And being especially hygienic when a cold sufferer is in your vicinity won't help, according to the latest research from the University of Virginia which indicates that the virus has much greater longevity than was previously thought.

The study found that one in two healthy people developed a cold after staying in a hotel room that had been occupied by a cold sufferer within the previous four days. Danger points were light switches, pens, telephones, handles, taps and TV controls. A proper hand wash five times a day, including after every episode of coughing, sneezing and cold blowing is recommended, and it involves more than simply running your hands under a cold tap. First wet the hands with warm running water prior to reaching for the soap.

Then rub hands together to make a lather, away from running water. Then wash the front and back of your hands between your fingers and under the nails, continue washing for 20 seconds or more. Finally, rinse hands under warm running water and dry them thoroughly with a clean towel or hair dryer.

Get some exercise It might be the last thing you want to do on a chilly evening but research from Loughborough University in the UK has shown that couch potatoes have a greater chance of getting a cold or flu than the moderately active. "Moderate exercise boosts white blood cells as well as increasing the concentration of antibodies in the saliva, protecting against respiratory infections, " says Mike Gleeson, professor of sport science and co-author of Immune Function in Sport and Exercise.

Generally, however, gentle walking is recommended during the winter months as opposed to strenuous physical exercise, which may leave you over tired and more susceptible to colds and flus. If you have the flu already however, don't think about exerting yourself. "One of the things you shouldn't do is go physical training because one of the consequences maybe to develop cardiomyiopathy heart failure due to viral infection, " says Dr Bill Tormey.

Get the right meds The chemist is the first port of call for most of us when we get colds and flus, and it makes sense to stock up before you catch either. There are many remedies available but seek your pharmacist's advice first and be particularly careful not to overdose on paracetemol. A good nasal spray or vapour rub will help you sleep at night but go to a doctor if you think you've developed a secondary bacterial infection (ie you're producing a lot of green gunk, not to put too fine a point on it), or you have any symptoms such as chest pain. These could indicate that you're developing pneumonia or pleurisy. Consider getting the flu jab if you're part of a high-risk group (if you have a heart condition, diabetes, autoimmune disease or are elderly) as it's 70%-90% effective.