The word fibromyalgia means pain (algia) coming from the muscles (my) and fibrous tissues (fibro) such as tendons and ligaments. Most people with fibromyalgia also have other symptoms in addition to the pains - see below. Therefore, fibromyalgia is sometimes called fibromyalgia syndrome (FMS). It is a persistent (chronic) condition. Fibromyalgia does not affect the joints, and so is not an arthritis.

The cause of fibromyalgia is not known. However, research has shown that people with fibromyalgia have certain subtle changes in some chemicals in the brain and nervous system. For example, there seems to be a minor change in the level of certain brain chemicals called neurotransmitters. These are the chemicals responsible for transmitting messages between nerves and between brain cells. Research studies have also shown that people with fibromyalgia tend to have an increased amount of a chemical called substance P in the fluid that bathes the brain and spinal cord (the cerebrospinal fluid (CSF)). This substance may be involved in the way pain messages are transmitted.

A current main theory is that people with fibromyalgia have an oversensitivity to pain signals in the brain. This is called central sensitisation. This may be due to various minor changes in brain chemicals. What triggers or causes these changes is not known.

The main symptoms are pains felt in many areas of the body, and tiredness (fatigue). Some people also develop other symptoms. The severity of symptoms varies from person to person.


Pain can occur in any area of the body. Typically, many areas of the body are affected, and some people feel the pain all over. The neck and back are the sites that are often the most painful. The severity of the pain can vary from day to day. The pains may be made worse by stress, cold or activity. After a night's sleep, you may also feel quite stiff for a few hours. Many areas of the body may also be quite tender.


Tiredness is common, and is sometimes severe. In some cases it is more distressing than the pain. It is also common to have a poor sleep pattern. You may wake feeling exhausted. Many people feel worst first thing in the morning, but improve by the afternoon. Even a small amount of activity may make you tired. The tiredness may cause you to have poor concentration.

Various other symptoms have been reported by people with fibromyalgia. Also, there are a number of other conditions that often occur at the same time as fibromyalgia. As a consequence, quite a number of other symptoms may occur in people with fibromyalgia. The following are perhaps the most common, but it is not an exhaustive list of every possible symptom that may occur:

  • Headaches are common.
  • Irritable bladder is common - you may need to go to the toilet more frequently than usual.
  • Irritable bowel syndrome occurs commonly in people with fibromyalgia - with tummy (abdominal) pains, sometimes with diarrhoea, constipation or bloating.
  • About 1 in 5 people with fibromyalgia also have restless legs syndrome (see separate leaflet called Restless Legs Syndrome for more detail).
  • Painful periods occur in some women with fibromyalgia.
  • Pins and needles in fingers and/or toes.
  • Some people describe a feeling as if their hands or feet are swollen (although they are not actually swollen).
  • Depression or anxiety develops in some people. It is not clear whether these are part of FMS, or develop as a result of having this condition.
  • Some people with fibromyalgia also have chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME).