Bleeding from the bottom (rectal bleeding) is a very common symptom. Up to 15% of adults have seen blood on their toilet paper during the previous six months.
The usual cause is a swollen blood vessel or a small tear around the anus.
However, it can also be the sign of a more serious health condition, including bowel cancer (colorectal cancer).
The quantity of blood that is passed varies widely. People generally become aware of rectal bleeding when they notice spots of blood on toilet paper or in underwear, or when a few drops of blood turn the water in the toilet bowl pink. Often these are tell-tale signs of piles (haemorrhoids) or an anal fissure, which is a small tear in the anus.
Others may notice larger quantities of blood being passed or that the blood is mixed in with stools.
As a general rule, bright red blood has been recently produced and means that the bleeding has come from the area around the anus. If the blood is darker, sticky or black it usually means that its origin is a bleed higher up the digestive tract.
That said, it is important not to try to diagnose the problem yourself but to seek medical advice about your symptoms.
The most common causes of rectal bleeding are:
Haemorrhoids, also called piles, are swollen blood vessels in the rectum or anus. These can cause bleeding when passing stools, an itchy feel around the anus and sometimes pain.
Haemorrhoids vary in size and can occur either inside or outside of the anus.
It is estimated that haemorrhoids affect between 4% and 25% of the population in the UK. Anyone can be affected by haemorrhoids, but pregnant women and people aged between 45 and 65 are particularly susceptible.
Around one in 10 people with haemorrhoids may need surgery, but a range of other treatments are available, including creams to reduce itching. Increasing the amount of fibre in your diet and drinking plenty of water can help you avoid constipation and the need to strain on the toilet - one of the main causes of haemorrhoids.
An anal fissure is a small tear in the lining of the anal canal. It is thought that most cases of anal fissures are caused when a large, hard stool is passed and damages the anal canal. This problem can also occur in people whose anal sphincter tone (the muscle that controls the anal opening) is too tight and cannot relax to pass the stool.
Usual symptoms of an anal fissure are a sharp pain when passing a stool followed by a burning sensation, and seeing bright red blood on the toilet paper.
There are two types of anal fissures: