Individuals with fibromyalgia are very sensitive to pain and therefore need to be wary and cautious of anything that increases pain.

A recent study just published ( August 2013) confirms the the previous understanding that the painkiller codeine can actually increase sensitivity to pain, without giving the same relief as morphine.
Many people with headaches often become worse after using codeine on a regular basis.
This is a potential problem for anyone with chronic pain who needs ongoing medication.

The occasional use is OK.
People who take codeine every now and then need not be concerned but heavy and ongoing codeine use could be detrimental for those who have chronic pain and or headache.

In addition codeine has the potential for addiction.
Whe purchasing over the counter products read the labels carefully.