High cholesterol is when you have too much of a fatty substance called cholesterol in your blood.
You're more likely to get high cholesterol if you're over 50, a man, you've been through the menopause, or you're of South Asian or sub-Saharan African origin. It can also run in families.
It can also be caused by eating fatty food, not exercising enough, being overweight, smoking and drinking alcohol.
You can lower your cholesterol by eating healthily and getting more exercise. Some people also need to take medicine.
Too much cholesterol can block your blood vessels. It makes you more likely to have heart problems or a stroke.
High cholesterol does not usually cause symptoms. You can only find out if you have it from a blood test.
Heart UK has information about inherited high cholesterol that starts at a young age (familial hypercholesterolaemia).