Who's affected?
Anyone can develop fibromyalgia, although it affects around 7 times as many women as men.
The condition typically develops between the ages of 30 and 50, but can occur in people of any age, including children and the elderly.
It's not clear exactly how many people are affected by fibromyalgia, although research has suggested it could be a relatively common condition.
Some estimates suggest nearly 1 in 20 people may be affected by fibromyalgia to some degree.
One of the main reasons it's not clear how many people are affected is because fibromyalgia can be a difficult condition to diagnose.
There's no specific test for the condition, and the symptoms can be similar to a number of other conditions.
Read more about diagnosing fibromyalgia.