I used to think these were synonyms, two words for the same condition. They are not the same thing and are rarely defined for us. Both are forms of neuropathic pain components in Fibromyalgia.
First let's start off with the basic definition of each:
Allodynia: A painful response to a non-painful stimuli.
Hyperalgesia: An exaggerated response to a painful stimuli.
Allodynia is only present in conditions related to central sensitization like; fibromyalgia, regional pain syndromes, neuropathy, post-hepatic neuralgia (shingles) and migraine. This condition causes normal sensations to become painful. Sensations that should be classified as non-painful are mixed up and classified as painful.
There are three forms of Allodynia:
Tactile: pain from touch or gentle pressure
Mechanical: pain from something moving across your skin or movement itself
Thermal: pain from heat or cold
This condition causes everyday sensations to become painful. Things as simple as a tag on a shirt, seams, jewelry, the elastic on pants, sleeves or socks, sheets on your legs, wind on your skin or even skin on skin. This sensation is described similarly to a bad sunburn. Some people experience a bruised feeling when a muscle is jarred, like when you are jogging or even tapping your toe. Others experienced pain like sparks, it's similar to the feel of a really light rain, little sparks that can feel cold or wet or sharp and stinging. Another description of Allodynia is the feeling of buzzing, vibration, pulsing, tingling or tightness throughout a part or parts in your body. This can make you feel disoriented and sometimes nauseated. Patients with Allodynia often complain that their skin feels sore.
Hyperalgesia is different than Allodynia in that the stimulus is already painful or annoying, however with hyperalgesia the pain is out of proportion. Essentially your pain is turned way up. So someone poking you in the thigh can feel like a charlie-horse or a small bruise can feel like a break. This is often why people with Fibromyalgia are told they are hypochondriacs or drama-queens because how could something so small or insignificant be so painful? It is also one of the main causes of fear and avoidance behaviors. We avoid situations that might cause pain because we are afraid of the level of pain. Things like bumping into things, or being hit by something, stubbing toes or fingers, scratches or cuts become terrifying our brain tells us -whoa no way!
Both of these conditions are very real. Both are caused by dysfunctional warning systems in your brain because of trauma, inflammation or disease. Sometimes these reactions can be halted if they are addressed early before they become chronic.
initially I found that massage made my Allodynia much worse, however after time it helped me desensitize a bit and now helps to control my overall pain. The heated pool helps ease my Hyperalgesia when I am working out. Trigger point injections help reduce my myofacial pain areas and in turn help reduce my Allodynia and Hyperalgesia. Atlas adjustments help reduce my migraines and tension headaches which also help control my Allodynia.
I should also mention that some medications can cause neuropathic pain. Also opioid treatment can train your body to stop making or receiving opioids and you can go into an opiod withdrawal syndrome that causes neuropathic pain.
Eccocannibioids are being studied as a treatment for neuropathic pain. Also combination opiod therapies with antagonists as well. Lidocaine patches and ointments as well as other topical analgesics can provide some relief of neuropathic pain. Usual therapies for neuropathic pain are trycyclics, anti-depressants, anti-seizure meds, and analgesics.
Ps. Aspartame is proven to worsen neuropathic pain, so is smoking.