You can help prevent colds by washing your hands regularly. This destroys bugs that you may have picked up from touching surfaces used by other people, such as light switches and door handles.
It's also important to keep the house and any household items such as cups, glasses and towels clean, especially if someone in your house is ill.
Top tip: If you get a cold, use disposable tissues instead of cloth handkerchiefs to avoid constantly reinfecting your own hands.
Read five surprising facts about the common cold.
Sore throats are common in winter and are almost always caused by viral infections. There's some evidence that changes in temperature, such as going from a warm, centrally heated room to the icy outdoors, can also affect the throat.
Top tip: One quick and easy remedy for a sore throat is to gargle with warm salty water. It won't heal the infection, but it has anti-inflammatory properties and can have a soothing effect. Dissolve one teaspoon of salt in a glass of part-cooled boiled water.
Find out how to treat a sore throat.
Cold air is a major trigger of asthma symptoms such as wheezing and shortness of breath. People with asthma should be especially careful in winter.
Top tip: Stay indoors on very cold, windy days. If you do go out, wear a scarf over your nose and mouth. Be extra vigilant about taking your regular medications, and keep rescue inhalers close by and in a warm place.
Get five tips to avoid cold-related asthma attacks.
Also known as the winter vomiting bug, norovirus is an extremely infectious stomach bug. It can strike all year round, but is more common in winter and in places such as hotels and schools. The illness is unpleasant, but it's usually over within a couple of days.
Top tip: When people are ill with vomiting and diarrhoea, it's important to drink plenty of fluids to prevent dehydration. Young children and the elderly are especially at risk. By drinking oral rehydration fluids (available from pharmacies), you can reduce the risk of dehydration.
Read about how to prevent food poisoning.
Many people with arthritis say their joints become more painful in winter, though it's not clear why this is the case. Only joint symptoms such as pain and stiffness are affected by the weather. There's no evidence that changes in the weather cause joint damage.
Top tip: Many people get a little depressed during the winter months, and this can make them perceive pain more acutely. Everything feels worse, including medical conditions. Daily exercise can boost a person's mental and physical state. Swimming is ideal as it's easy on the joints.
Read about how to get started with swimming for fitness.
Most of us recognise that cold sores are a sign that we're run down or under stress. While there's no cure for cold sores, you can reduce the chances of getting one by looking after yourself through winter.
Top tip: Every day, do things that make you feel less stressed, such as having a hot bath, going for a walk in the park, or watching one of your favourite films.
Read about the top 10 stress busters.
Heart attacks are more common in winter. This may be because cold snaps increase blood pressure and put more strain on the heart. Your heart also has to work harder to maintain body heat when it's cold.
Top tip: Stay warm in your home. Keep the main rooms you use at 21C (70F) and use a hot water bottle or electric blanket to keep warm in bed. Wrap up warm when you go out and wear a hat, scarf and gloves.
More tips on how to keep warm and well.
Raynaud's phenomenon is a common condition that makes your fingers and toes change colour and become very painful in cold weather. Fingers can go white, then blue, then red, and throb and tingle. It's a sign of poor circulation in the small blood vessels of the hands and feet. In severe cases, medication can help, but most people live with their symptoms.
Top tip: Don't smoke or drink caffeine (they can both worsen symptoms) and always wear warm gloves, socks and shoes when going out in cold weather.
Get advice on how to stop smoking.
Dry skin is a common condition and is often worse during the winter, when environmental humidity is low.
Moisturising is essential during winter. Contrary to popular belief, moisturising lotions and creams aren't absorbed by the skin. Instead, they act as a sealant to stop the skin's natural moisture evaporating away.
The best time to apply moisturiser is after a bath or shower while your skin is still moist, and again at bedtime.
Top tip: Have warm, rather than hot, showers. Water that is too hot makes skin feel more dry and itchy. Hot water will also make your hair look dull and dry.
Flu is a major killer of vulnerable people. People aged 65 and over and people with long-term health conditions, including diabetes and kidney disease, are particularly at risk.
The best way to prevent getting flu is to have the flu jab (or flu nasal spray for children aged 2 to 18). The flu vaccine gives good protection against flu and lasts for one year.
Top tip: Find out if you're at risk of getting flu by asking your GP, or read our article on who should have the flu jab. If you're in a high-risk group, see your GP to get the vaccination.
Now, read about how to stay well in very cold weather.