What causes vasculitis?
There's no single cause of vasculitis, and in most cases the exact cause is unknown. We know that vasculitis isn't directly inherited through the genes we get from our parents, but genetic factors do play a part as several cases can occur in the same family. Your genes could make you more likely to develop the condition, in which case it may only take a small trigger (such as an infection or drugs) to start this off.
We also know that some types of vasculitis – for example, those affecting the small blood vessels – can be related to infections, particularly those associated with hepatitis. Some cases of vasculitis occur after treatment with certain drugs, for example propylthiouracil (used to treat thyroid disease) and allopurinol (used to treat gout), as well as non-steroidal anti-inflammatory drugs (NSAIDs) and antibiotics.
It's thought that most forms of vasculitis are a type of autoimmune disease. This means that your body's defence mechanisms aren't doing their normal job of fighting infections, but instead attack a healthy part of the body, causing inflammation.