According to the NHS, 2017 will be the worst flu season in history. Great!

And even people who have the flu jab are still at risk, as there are different strains of the influenza virus – and the severity of your symptoms depends on which one you get.

[Read more: 6 ways to boost your vitamin D intake]

Healthy Living Pharmacist, Deborah Evans, says: “Thousands of people die each winter due to complications of the flu. It is much worse than a cold with severe symptoms that come on quickly and can cause you to stay in bed for several days, unable to do anything other than rest. It can become very serious for the elderly, young and those with other conditions and can result in needing to go to hospital.”

Even for the healthiest of us, flu recovery can take up to a week, but it’s our clever immune system response that causes many of the nasty symptoms of the flu.

Here’s Healthy Living’s guide to those symptoms…

High fever

One the common symptoms of the flu is a high fever. We get a high fever because the flu virus quickly multiplies at the normal body temperature, which is 37.5 degrees. Your body’s immune system reacts to this by raising the normal body temperature in an attempt to prevent the virus multiplying whilst also attempting to kill the virus.

Your high temperature can also cause blood vessels to dilate. This increases the pressure in your head causing the pain of headaches. However, if your temperature becomes too high and your head aches too much, you can take an ibuprofen to reduce your temperature and relieve the pain.

Coughing

Coughing is another symptom of the body protecting itself against the flu virus, it is a bodily reflex that helps keep our respiratory system clear when it becomes inflamed or clogged by mucus.

Deborah advises: “When you sneeze or cough, don’t cover your face with your hand but cough or sneeze into a tissue and then bin it. Viruses can stay alive for hours after they’ve left your (or someone else’s) body, so wash your hands or use an alcohol rub and avoid touching your face.’

GP Dr Sarah Jarvis says: “The vast majority of viral coughs will settle on their own in time - antibiotics won’t help, but the right cough medicine can.”

Dehydration

There are many ways that you become dehydrated whilst you are suffering from the flu. Most obviously, when you start to suffer from a fever, you are likely to be sweating much more than usual, therefore whilst you are not taking part in any physical activity, you are losing important salts and minerals.

Further to this, when your body temperature increases, as does your metabolism, a metabolic reaction uses both water and oxygen, making you dehydrated. Even if you don’t suffer a full-blown fever, your body temperature may still be higher than normal, causing dehydration. Commonly, we also tend not to eat and drink as much as we normally would due to loss of appetite. If you want a quick recovery, don’t forget to hydrate.

[Read more: Flu jabs: Who can get one on the NHS, will the vaccine give me flu and is flu serious?]

Nasal congestion

This is a symptom that’s common with both a cold and flu. Whilst irritating and uncomfortable, it is another sign of your body’s natural defence mechanisms getting to work. When your body detects the flu’s viral infection, it sends white blood cells to the source of the infection which then releases molecules that cause the mucous membranes to swell and produce mucus. Both the swelling and excess mucus can make us feel that awful nasal congestion.

To relieve the stuffed-up feeling, and clear the airways, try eucalyptus oil. Symptoms can be relieved by inhaling the vapour, either on a handkerchief or adding to hot water.

Fatigue

At any given time, one in five people feel unusually tired. Whilst for many this could be due to a chronic illness, for some it could be due to a recent viral infection, such as the flu. The flu can make you feel fatigued, both when the infection is taking hold and long after. Your body cells do a lot to fight the infection and, in the process, your cells are using more energy than they normally would. It is this energy drain that can leave you feeling tired and lacking your usual get up and go. After a bout of the virus, it will take a while to build up your energy and stamina, so make sure you get plenty of rest.

Dr Roger Henderson, media medic and family GP, says: “When your body is under stress, you are more susceptible to the viral infections that cause coughs, colds and flu, so keep calm and stay healthy.”