The problem can also develop if blood is lost quicker than the body can replace it, for example, during a woman's excessively heavy monthly periods, bleeding from an ulcer, or due to the continuous use of drugs for rheumatism, such as aspirins and non-steroidal inflammatory drugs.
Low dose aspirins used in heart disease and for "little strokes" do not have this bleeding from the bowel effect, neither does paracetamol.
Lastly, bleeding from the bowel can be due to cancer or piles - bright red bleeding is usually due to the latter. Bleeding from higher up the bowel is either not noticeable or causes tarry, black motions.
It is always best to see a doctor if you are suffering from any of these symptoms. You may not be suffering from anaemia, but you may have another problem which needs treating.
Many articles taken from 'A word with the doctor', by Dr. John Windsor.