Colds and flu share some of the same symptoms (cough, sore throat), but are caused by different viruses. Flu can be much more serious than a cold.
If you’re generally fit and healthy, you can usually manage the symptoms of a cold or flu yourself without seeing a doctor. Look after yourself by resting, drinking non-alcoholic fluids to avoid dehydration and avoiding strenuous activity. Painkillers such as ibuprofenor paracetamol can relieve aches and pains.
There are around 200 viruses that cause colds and just three that cause flu. There are many strains of these flu viruses, and the vaccine changes every year to protect against the most common ones.
Colds cause more nasal problems, such as blocked nose, than flu. Fever, fatigue and muscle aches are more likely and more severe with flu.
Symptoms of a cold include:
- runny nose – beginning with clear mucus that develops into thicker, green mucus as the cold progresses
- blocked nose
- sore throat
People with a cold may also suffer with a mild fever, earache, tiredness and headache. Symptoms develop over one or two days and gradually get better after a few days. Some colds can last for up to two weeks.
According to the Common Cold Centre in Cardiff, a cold is most contagious during the early stages, when the person has a runny nose and sore throat.
Flu usually comes on much more quickly than a cold, and symptoms include:
- sudden fever of 38-40C (100-104F)
- muscle aches and pains
- feeling exhausted and needing to lie down
- a dry, chesty cough
A person with flu may also have a runny nose and be prone to sneezing, but these are not usually the defining symptoms of flu.
Flu symptoms appear one to three days after infection and most people recover within a week, although you may feel tired for longer. A severe cold can also cause muscle aches and fever, so it can be hard to tell the difference.
Whether it’s a cold or flu, get medical help if you either:
- have a chronic condition (such as asthma, diabetes or heart disease)
- have a very high fever as well as an unusually severe headache or abdominal or chest pain
People more at risk
Some people need to take extra care as they’re more at risk of serious chest complications, such as pneumonia and bronchitis. People over 65 are more at risk of complications. People under 65, including children, are more at risk of complications if they have:
- serious heart or chest complaints, including asthma
- serious kidney disease or liver disease
- lowered immunity due to disease or medical treatment
- had a stroke or transient ischaemic attack (TIA)
Everyone in an at-risk group is eligible for a free flu vaccination, which is the best protection against the virus. Find out who is offered the flu jab, including all pregnant women.
Stop the viruses spreading
Cold and flu viruses are spread by droplets that are coughed or sneezed out by an infected person. Other people can breathe in these droplets or transfer the droplets to their eyes or nose, via their fingers.
Protect yourself and others against colds and flu by:
- coughing or sneezing into a tissue
- throwing a used tissue away as soon as possible
- washing your hands as soon as possible
- having a flu jab every year if you’re in an at-risk group
Colds and flu viruses can also be passed on via infected droplets on objects or surfaces, such as door handles. You can help to prevent passing on or getting colds and flu by washing your hands regularly, and avoiding touching your eyes and nose.
To check your symptoms, use our colds and flu symptom checker.