Allodynia is a condition in which something 
that does not ordinarily cause pain actually 
does cause pain. An example would be 
feeling pain when touched lightly by a cotton 
T-shirt or slightly cold water.  When alloydynia  
occurs in response to mildly hot or cold 
temperature sensations it is known as thermal 
allodynia. When it occurs in response to 
physical stimulation, it is known as tactile 
allodynia or mechanical allodynia. In dynamic 
mechanical allodynia there is pain in 
response to brushing. 
 
In static mechanical allodynia, there is pain in response to light touch/pressure.  
Abnormal functioning of pain receptors (known as nocireceptors) causes allodynia. 
Another cause of allodynia is sensitization, in which repeated stimulation of nerve 
endings causes those nerve endings to increase their responsiveness. 
Allodynia is a feature of pain syndromes such as migraines, nerve damage, and 
tenderness in the muscles and bones, stiffness, fatigue, spasms, and severe sleep  
difficulties. 
 
Allodynia can also be caused by nerve damage from the varicella 
zoster virus (a type of herpes virus). It can also be caused by 
complex regional pain syndrome, which is a chronic worsening 
disease that causes severe pain, skin changes, and swelling. 
Allodynia can also be caused by some types of stem cells used to  
treat nerve damage such as spinal cord injury.  
Stem cells are cells that have the ability to divide indefinitely and turn 
into a number of different specialized cells. There are numerous 
medications used to treat different forms of allodynia. Allodynia is 
different from hyperalgesia which is excessive sensitivity to painful  
stimuli. 
 
Allodynia is associated with dysesthesia. Dysesthesia is pain or an uncomfortable sensation(s) after  
being touched by an ordinary stimulus or even in the absence of stimulation. Allodynia comes from the 
Greek word "allos" meaning "other," and the Greek word "odyne" meaning "pain." Put the words together 
and you get "other pain."