You may need to take several different types of medicines for fibromyalgia, including painkillers and antidepressants. Different medicines are described in more detail below.
Painkillers
If you have fibromyalgia, you can treat your pain using simple painkillers, such as paracetamol, available over the counter from a pharmacy. Always read the manufacturer’s instructions.
If paracetamol is not effective, your GP (or another healthcare professional treating you) may prescribe a stronger painkiller, such as codeine or tramadol. Research has found that tramadol can improve pain and may also help you function better in your daily activities.
Side effects of tramadol include:
diarrhoea
fatigue (extreme tiredness)
withdrawal symptoms if you stop taking it
source:http://www.nhs.uk/Conditions/Fibromyalgia/Pages/Treatment.aspx