Postherpetic neuralgia, also known as PHN, is a painful health condition of recurring or persistent pain that affects your nerves and skin. Usually in the area of the body that has undergone an outbreak of herpes zoster, postherpetic neuralgia is commonly referred to as shingles.
Shingles is caused by the reactivation of the varicella-zoster virus. It comes as a painful, blistering skin rash that can be extremely uncomfortable. The virus is mostly contracted at childhood or adolescence as chickenpox.  What happens is that, the virus remains dormant in the body’s nerve cells and can reactivate years later after childhood.
Neuralgia is a neuropathic pain that occurs along the course of a nerve, while postherpetic neuralgia is the term used to refer to the condition of when the pain caused by shingles doesn’t go away even after the rash and blister clear up. Postherpetic neuralgia occur when the shingles outbreak damages the nerves, it is the most common complication of shingles.
Postherpetic neuralgia causes the nerves to not be able to send messages from the skin to the brain, since the nerves are damaged. This result in chronic severe pain that can last for months. The pain comes from inside the nervous system, often referred to as a pinched nerve or trapped nerve. It is usually a sensation of intense burning or stabbing, and it may feel as though it is shooting along the course of the affected nerve. A 2017 review showed that about 20 percent of the people who get shingles develop PHN.
Symptoms of Postherpetic Neuralgia
Postherpetic neuralgia’s main symptom is pain alongside a blistering rash. The pain can be extremely severe. It is an allodynia type of pain, which is due to stimulus that does not normally provoke pain. The neuropathic pain is described as a burning, sharp, jabbing, deep, and aching sensation. The pain and discomfort can last for months and increases when there is any slight pressure, or contact with the area.
Other symptoms include:
- Numbness of the area
- Headaches 
- Sensitivity to temperature
- Sensitivity to touch
In rare complications, if the affected nerve controls muscle movement, it can lead to muscle weakness or paralysis. PHN causes extreme discomfort and makes it hard to carry out some daily activity.