Painful piles can be caused by inflammation, but there are also other influencing factors. Haemorrhoids are located in a complex environment that is relatively moist and dirty, so they can easily accumulate bacteria, fungi and viruses, which can induce infection and inflammatory lesions. However, there are also many cases of painful haemorrhoids that are caused by non-infectious factors such as acute venous thrombosis which can also cause painful haemorrhoids.